[ruby/prism] Tests overhaul

https://github.com/ruby/prism/commit/6f886be0a4

lib/prism/ffi.rb

@@ -200,8 +200,8 @@ module Prism
 
   class << self
     # Mirror the Prism.dump API by using the serialization API.
-    def dump(code, **options)
-      LibRubyParser::PrismString.with_string(code) { |string| dump_common(string, options) }
+    def dump(source, **options)
+      LibRubyParser::PrismString.with_string(source) { |string| dump_common(string, options) }
     end
 
     # Mirror the Prism.dump_file API by using the serialization API.
@@ -302,6 +302,27 @@ module Prism
       !parse_file_success?(filepath, **options)
     end
 
+    # Mirror the Prism.profile API by using the serialization API.
+    def profile(source, **options)
+      LibRubyParser::PrismString.with_string(source) do |string|
+        LibRubyParser::PrismBuffer.with do |buffer|
+          LibRubyParser.pm_serialize_parse(buffer.pointer, string.pointer, string.length, dump_options(options))
+          nil
+        end
+      end
+    end
+
+    # Mirror the Prism.profile_file API by using the serialization API.
+    def profile_file(filepath, **options)
+      LibRubyParser::PrismString.with_file(filepath) do |string|
+        LibRubyParser::PrismBuffer.with do |buffer|
+          options[:filepath] = filepath
+          LibRubyParser.pm_serialize_parse(buffer.pointer, string.pointer, string.length, dump_options(options))
+          nil
+        end
+      end
+    end
+
     private
 
     def dump_common(string, options) # :nodoc:

lib/prism/translation/ruby_parser.rb

@@ -485,9 +485,9 @@ module Prism
         def visit_constant_path_target_node(node)
           inner =
             if node.parent.nil?
-              s(node, :colon3, node.child.name)
+              s(node, :colon3, node.name)
             else
-              s(node, :colon2, visit(node.parent), node.child.name)
+              s(node, :colon2, visit(node.parent), node.name)
             end
 
           s(node, :const, inner)

test/prism/api/command_line_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class CommandLineTest < TestCase
@@ -67,7 +67,7 @@ module Prism
     end
 
     def test_command_line_x_implicit
-      result = Prism.parse(<<~RUBY)
+      result = Prism.parse_statement(<<~RUBY)
         #!/bin/bash
         exit 1
 
@@ -75,18 +75,18 @@ module Prism
         1
       RUBY
 
-      assert_kind_of IntegerNode, result.value.statements.body.first
+      assert_kind_of IntegerNode, result
     end
 
     def test_command_line_x_explicit
-      result = Prism.parse(<<~RUBY, command_line: "x")
+      result = Prism.parse_statement(<<~RUBY, command_line: "x")
         exit 1
 
         #!/usr/bin/env ruby
         1
       RUBY
 
-      assert_kind_of IntegerNode, result.value.statements.body.first
+      assert_kind_of IntegerNode, result
     end
 
     def test_command_line_x_implicit_fail

test/prism/api/dump_test.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+return if ENV["PRISM_BUILD_MINIMAL"]
+
+require_relative "../test_helper"
+
+module Prism
+  class DumpTest < TestCase
+    Fixture.each do |fixture|
+      define_method(fixture.test_name) { assert_dump(fixture) }
+    end
+
+    def test_dump
+      filepath = __FILE__
+      source = File.read(filepath, binmode: true, external_encoding: Encoding::UTF_8)
+
+      assert_equal Prism.lex(source, filepath: filepath).value, Prism.lex_file(filepath).value
+      assert_equal Prism.dump(source, filepath: filepath), Prism.dump_file(filepath)
+
+      serialized = Prism.dump(source, filepath: filepath)
+      ast1 = Prism.load(source, serialized).value
+      ast2 = Prism.parse(source, filepath: filepath).value
+      ast3 = Prism.parse_file(filepath).value
+
+      assert_equal_nodes ast1, ast2
+      assert_equal_nodes ast2, ast3
+    end
+
+    def test_dump_file
+      assert_nothing_raised do
+        Prism.dump_file(__FILE__)
+      end
+
+      error = assert_raise Errno::ENOENT do
+        Prism.dump_file("idontexist.rb")
+      end
+
+      assert_equal "No such file or directory - idontexist.rb", error.message
+
+      assert_raise TypeError do
+        Prism.dump_file(nil)
+      end
+    end
+
+    private
+
+    def assert_dump(fixture)
+      source = fixture.read
+
+      result = Prism.parse(source, filepath: fixture.path)
+      dumped = Prism.dump(source, filepath: fixture.path)
+
+      assert_equal_nodes(result.value, Prism.load(source, dumped).value)
+    end
+  end
+end

test/prism/api/parse_comments_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class ParseCommentsTest < TestCase
@@ -17,5 +17,17 @@ module Prism
       assert_kind_of Array, comments
       assert_equal 1, comments.length
     end
+
+    def test_parse_file_comments_error
+      error = assert_raise Errno::ENOENT do
+        Prism.parse_file_comments("idontexist.rb")
+      end
+
+      assert_equal "No such file or directory - idontexist.rb", error.message
+
+      assert_raise TypeError do
+        Prism.parse_file_comments(nil)
+      end
+    end
   end
 end

test/prism/api/parse_stream_test.rb

@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
-require "stringio"
+require_relative "../test_helper"
 
 module Prism
   class ParseStreamTest < TestCase
@@ -10,7 +9,7 @@ module Prism
       result = Prism.parse_stream(io)
 
       assert result.success?
-      assert_kind_of Prism::CallNode, result.value.statements.body.first
+      assert_kind_of Prism::CallNode, result.statement
     end
 
     def test_multi_line
@@ -18,8 +17,8 @@ module Prism
       result = Prism.parse_stream(io)
 
       assert result.success?
-      assert_kind_of Prism::CallNode, result.value.statements.body.first
-      assert_kind_of Prism::CallNode, result.value.statements.body.last
+      assert_kind_of Prism::CallNode, result.statement
+      assert_kind_of Prism::CallNode, result.statement
     end
 
     def test_multi_read
@@ -27,7 +26,7 @@ module Prism
       result = Prism.parse_stream(io)
 
       assert result.success?
-      assert_kind_of Prism::CallNode, result.value.statements.body.first
+      assert_kind_of Prism::CallNode, result.statement
     end
 
     def test___END__

test/prism/api/parse_success_test.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class ParseSuccessTest < TestCase
+    def test_parse_success?
+      assert Prism.parse_success?("1")
+      refute Prism.parse_success?("<>")
+    end
+
+    def test_parse_file_success?
+      assert Prism.parse_file_success?(__FILE__)
+    end
+  end
+end

test/prism/api/parse_test.rb

@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class ParseTest < TestCase
+    def test_parse_empty_string
+      result = Prism.parse("")
+      assert_equal [], result.value.statements.body
+    end
+
+    def test_parse_takes_file_path
+      filepath = "filepath.rb"
+      result = Prism.parse("def foo; __FILE__; end", filepath: filepath)
+
+      assert_equal filepath, find_source_file_node(result.value).filepath
+    end
+
+    def test_parse_takes_line
+      line = 4
+      result = Prism.parse("def foo\n __FILE__\nend", line: line)
+
+      assert_equal line, result.value.location.start_line
+      assert_equal line + 1, find_source_file_node(result.value).location.start_line
+
+      result = Prism.parse_lex("def foo\n __FILE__\nend", line: line)
+      assert_equal line, result.value.first.location.start_line
+    end
+
+    def test_parse_takes_negative_lines
+      line = -2
+      result = Prism.parse("def foo\n __FILE__\nend", line: line)
+
+      assert_equal line, result.value.location.start_line
+      assert_equal line + 1, find_source_file_node(result.value).location.start_line
+
+      result = Prism.parse_lex("def foo\n __FILE__\nend", line: line)
+      assert_equal line, result.value.first.location.start_line
+    end
+
+    def test_parse_file
+      node = Prism.parse_file(__FILE__).value
+      assert_kind_of ProgramNode, node
+
+      error = assert_raise Errno::ENOENT do
+        Prism.parse_file("idontexist.rb")
+      end
+
+      assert_equal "No such file or directory - idontexist.rb", error.message
+
+      assert_raise TypeError do
+        Prism.parse_file(nil)
+      end
+    end
+
+    private
+
+    def find_source_file_node(program)
+      queue = [program]
+      while (node = queue.shift)
+        return node if node.is_a?(SourceFileNode)
+        queue.concat(node.compact_child_nodes)
+      end
+    end
+  end
+end

test/prism/bom_test.rb

@@ -2,7 +2,7 @@
 
 # Don't bother checking this on these engines, this is such a specific Ripper
 # test.
-return if RUBY_ENGINE == "jruby" || RUBY_ENGINE == "truffleruby"
+return if RUBY_ENGINE != "ruby"
 
 require_relative "test_helper"
 

test/prism/encoding/encodings_test.rb

@@ -0,0 +1,101 @@
+# frozen_string_literal: true
+
+return if RUBY_ENGINE != "ruby"
+
+require_relative "../test_helper"
+
+module Prism
+  class EncodingsTest < TestCase
+    class ConstantContext < BasicObject
+      def self.const_missing(const)
+        const
+      end
+    end
+
+    class IdentifierContext < BasicObject
+      def method_missing(name, *)
+        name
+      end
+    end
+
+    # These test that we're correctly parsing codepoints for each alias of each
+    # encoding that prism supports.
+    each_encoding do |encoding, range|
+      (encoding.names - %w[external internal filesystem locale]).each do |name|
+        define_method(:"test_encoding_#{name}") do
+          assert_encoding(encoding, name, range)
+        end
+      end
+    end
+
+    private
+
+    def assert_encoding_constant(name, character)
+      source = "# encoding: #{name}\n#{character}"
+      expected = ConstantContext.new.instance_eval(source)
+
+      result = Prism.parse(source)
+      assert result.success?
+
+      actual = result.value.statements.body.last
+      assert_kind_of ConstantReadNode, actual
+      assert_equal expected, actual.name
+    end
+
+    def assert_encoding_identifier(name, character)
+      source = "# encoding: #{name}\n#{character}"
+      expected = IdentifierContext.new.instance_eval(source)
+
+      result = Prism.parse(source)
+      assert result.success?
+
+      actual = result.value.statements.body.last
+      assert_kind_of CallNode, actual
+      assert_equal expected, actual.name
+    end
+
+    # Check that we can properly parse every codepoint in the given encoding.
+    def assert_encoding(encoding, name, range)
+      # I'm not entirely sure, but I believe these codepoints are incorrect in
+      # their parsing in CRuby. They all report as matching `[[:lower:]]` but
+      # then they are parsed as constants. This is because CRuby determines if
+      # an identifier is a constant or not by case folding it down to lowercase
+      # and checking if there is a difference. And even though they report
+      # themselves as lowercase, their case fold is different. I have reported
+      # this bug upstream.
+      case encoding
+      when Encoding::UTF_8, Encoding::UTF_8_MAC, Encoding::UTF8_DoCoMo, Encoding::UTF8_KDDI, Encoding::UTF8_SoftBank, Encoding::CESU_8
+        range = range.to_a - [
+          0x01c5, 0x01c8, 0x01cb, 0x01f2, 0x1f88, 0x1f89, 0x1f8a, 0x1f8b,
+          0x1f8c, 0x1f8d, 0x1f8e, 0x1f8f, 0x1f98, 0x1f99, 0x1f9a, 0x1f9b,
+          0x1f9c, 0x1f9d, 0x1f9e, 0x1f9f, 0x1fa8, 0x1fa9, 0x1faa, 0x1fab,
+          0x1fac, 0x1fad, 0x1fae, 0x1faf, 0x1fbc, 0x1fcc, 0x1ffc,
+        ]
+      when Encoding::Windows_1253
+        range = range.to_a - [0xb5]
+      end
+
+      range.each do |codepoint|
+        character = codepoint.chr(encoding)
+
+        if character.match?(/[[:alpha:]]/)
+          if character.match?(/[[:upper:]]/)
+            assert_encoding_constant(name, character)
+          else
+            assert_encoding_identifier(name, character)
+          end
+        elsif character.match?(/[[:alnum:]]/)
+          assert_encoding_identifier(name, "_#{character}")
+        else
+          next if ["/", "{"].include?(character)
+
+          source = "# encoding: #{name}\n/(?##{character})/\n"
+          assert Prism.parse_success?(source), "Expected #{source.inspect} to parse successfully."
+        end
+      rescue RangeError
+        source = "# encoding: #{name}\n\\x#{codepoint.to_s(16)}"
+        assert Prism.parse_failure?(source)
+      end
+    end
+  end
+end

test/prism/encoding/regular_expression_encoding_test.rb

@@ -0,0 +1,131 @@
+# frozen_string_literal: true
+
+return unless defined?(RubyVM::InstructionSequence)
+return if RubyVM::InstructionSequence.compile("").to_a[4][:parser] == :prism
+
+require_relative "../test_helper"
+
+module Prism
+  class RegularExpressionEncodingTest < TestCase
+    each_encoding do |encoding, _|
+      define_method(:"test_regular_expression_encoding_flags_#{encoding.name}") do
+        assert_regular_expression_encoding_flags(encoding, ["/a/", "/ą/", "//"])
+      end
+
+      escapes = ["\\x00", "\\x7F", "\\x80", "\\xFF", "\\u{00}", "\\u{7F}", "\\u{80}", "\\M-\\C-?"]
+      escapes = escapes.concat(escapes.product(escapes).map(&:join))
+
+      define_method(:"test_regular_expression_escape_encoding_flags_#{encoding.name}") do
+        assert_regular_expression_encoding_flags(encoding, escapes.map { |e| "/#{e}/" })
+      end
+
+      ["n", "u", "e", "s"].each do |modifier|
+        define_method(:"test_regular_expression_encoding_modifiers_/#{modifier}_#{encoding.name}") do
+          regexp_sources = ["abc", "garçon", "\\x80", "gar\\xC3\\xA7on", "gar\\u{E7}on", "abc\\u{FFFFFF}", "\\x80\\u{80}" ]
+
+          assert_regular_expression_encoding_flags(
+            encoding,
+            regexp_sources.product(["n", "u", "e", "s"]).map { |r, modifier| "/#{r}/#{modifier}" }
+          )
+        end
+      end
+    end
+
+    private
+
+    def assert_regular_expression_encoding_flags(encoding, regexps)
+      regexps.each do |regexp|
+        regexp_modifier_used = regexp.end_with?("/u") || regexp.end_with?("/e") || regexp.end_with?("/s") || regexp.end_with?("/n")
+        source = "# encoding: #{encoding.name}\n#{regexp}"
+
+        encoding_errors = ["invalid multibyte char", "escaped non ASCII character in UTF-8 regexp", "differs from source encoding"]
+        skipped_errors = ["invalid multibyte escape", "incompatible character encoding", "UTF-8 character in non UTF-8 regexp", "invalid Unicode range", "invalid Unicode list"]
+
+        # TODO (nirvdrum 21-Feb-2024): Prism currently does not handle Regexp validation unless modifiers are used. So, skip processing those errors for now: https://github.com/ruby/prism/issues/2104
+        unless regexp_modifier_used
+          skipped_errors += encoding_errors
+          encoding_errors.clear
+        end
+
+        expected =
+          begin
+            eval(source).encoding
+          rescue SyntaxError => error
+            if encoding_errors.find { |e| error.message.include?(e) }
+              error.message.split("\n").map { |m| m[/: (.+?)$/, 1] }
+            elsif skipped_errors.find { |e| error.message.include?(e) }
+              next
+            else
+              raise
+            end
+          end
+
+        actual =
+          Prism.parse(source).then do |result|
+            if result.success?
+              regexp = result.statement
+
+              actual_encoding = if regexp.forced_utf8_encoding?
+                Encoding::UTF_8
+              elsif regexp.forced_binary_encoding?
+                Encoding::ASCII_8BIT
+              elsif regexp.forced_us_ascii_encoding?
+                Encoding::US_ASCII
+              elsif regexp.ascii_8bit?
+                Encoding::ASCII_8BIT
+              elsif regexp.utf_8?
+                Encoding::UTF_8
+              elsif regexp.euc_jp?
+                Encoding::EUC_JP
+              elsif regexp.windows_31j?
+                Encoding::Windows_31J
+              else
+                encoding
+              end
+
+              if regexp.utf_8? && actual_encoding != Encoding::UTF_8
+                raise "expected regexp encoding to be UTF-8 due to '/u' modifier, but got #{actual_encoding.name}"
+              elsif regexp.ascii_8bit? && (actual_encoding != Encoding::ASCII_8BIT && actual_encoding != Encoding::US_ASCII)
+                raise "expected regexp encoding to be ASCII-8BIT or US-ASCII due to '/n' modifier, but got #{actual_encoding.name}"
+              elsif regexp.euc_jp? && actual_encoding != Encoding::EUC_JP
+                raise "expected regexp encoding to be EUC-JP due to '/e' modifier, but got #{actual_encoding.name}"
+              elsif regexp.windows_31j? && actual_encoding != Encoding::Windows_31J
+                raise "expected regexp encoding to be Windows-31J due to '/s' modifier, but got #{actual_encoding.name}"
+              end
+
+              if regexp.utf_8? && regexp.forced_utf8_encoding?
+                raise "the forced_utf8 flag should not be set when the UTF-8 modifier (/u) is used"
+              elsif regexp.ascii_8bit? && regexp.forced_binary_encoding?
+                raise "the forced_ascii_8bit flag should not be set when the UTF-8 modifier (/u) is used"
+              end
+
+              actual_encoding
+            else
+              errors = result.errors.map(&:message)
+
+              if errors.last&.include?("UTF-8 mixed within")
+                nil
+              else
+                errors
+              end
+            end
+          end
+
+        # TODO (nirvdrum 22-Feb-2024): Remove this workaround once Prism better maps CRuby's error messages.
+        # This class of error message is tricky. The part not being compared is a representation of the regexp.
+        # Depending on the source encoding and any encoding modifiers being used, CRuby alters how the regexp is represented.
+        # Sometimes it's an MBC string. Other times it uses hexadecimal character escapes. And in other cases it uses
+        # the long-form Unicode escape sequences. This short-circuit checks that the error message is mostly correct.
+        if expected.is_a?(Array) && actual.is_a?(Array)
+          if expected.last.start_with?("/.../n has a non escaped non ASCII character in non ASCII-8BIT script:") &&
+              actual.last.start_with?("/.../n has a non escaped non ASCII character in non ASCII-8BIT script:")
+              expected.last.clear
+              actual.last.clear
+          end
+        end
+
+        assert_equal expected, actual
+      end
+    end
+  end
+end

test/prism/encoding/string_encoding_test.rb

@@ -0,0 +1,136 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class StringEncodingTest < TestCase
+    each_encoding do |encoding, _|
+      define_method(:"test_#{encoding.name}") do
+        assert_encoding(encoding)
+      end
+    end
+
+    def test_coding
+      actual = Prism.parse_statement("# coding: utf-8\n'string'").unescaped.encoding
+      assert_equal Encoding::UTF_8, actual
+    end
+
+    def test_coding_with_whitespace
+      actual = Prism.parse_statement("# coding \t \r  \v   :     \t \v    \r   ascii-8bit \n'string'").unescaped.encoding
+      assert_equal Encoding::ASCII_8BIT, actual
+    end
+
+    def test_emacs_style
+      actual = Prism.parse_statement("# -*- coding: utf-8 -*-\n'string'").unescaped.encoding
+      assert_equal Encoding::UTF_8, actual
+    end
+
+    def test_utf_8_unix
+      actual = Prism.parse_statement("# coding: utf-8-unix\n'string'").unescaped.encoding
+      assert_equal Encoding::UTF_8, actual
+    end
+
+    def test_utf_8_dos
+      actual = Prism.parse_statement("# coding: utf-8-dos\n'string'").unescaped.encoding
+      assert_equal Encoding::UTF_8, actual
+    end
+
+    def test_utf_8_mac
+      actual = Prism.parse_statement("# coding: utf-8-mac\n'string'").unescaped.encoding
+      assert_equal Encoding::UTF_8, actual
+    end
+
+    def test_utf_8_star
+      actual = Prism.parse_statement("# coding: utf-8-*\n'string'").unescaped.encoding
+      assert_equal Encoding::UTF_8, actual
+    end
+
+    def test_first_lexed_token
+      encoding = Prism.lex("# encoding: ascii-8bit").value[0][0].value.encoding
+      assert_equal Encoding::ASCII_8BIT, encoding
+    end
+
+    if !ENV["PRISM_BUILD_MINIMAL"]
+      # This test may be a little confusing. Basically when we use our strpbrk,
+      # it takes into account the encoding of the file.
+      def test_strpbrk_multibyte
+        result = Prism.parse(<<~RUBY)
+          # encoding: Shift_JIS
+          %w[\x81\x5c]
+        RUBY
+
+        assert(result.errors.empty?)
+        assert_equal(
+          (+"\x81\x5c").force_encoding(Encoding::Shift_JIS),
+          result.statement.elements.first.unescaped
+        )
+      end
+
+      def test_slice_encoding
+        slice = Prism.parse("# encoding: Shift_JIS\nア").value.slice
+        assert_equal (+"ア").force_encoding(Encoding::SHIFT_JIS), slice
+        assert_equal Encoding::SHIFT_JIS, slice.encoding
+      end
+
+      def test_multibyte_escapes
+        [
+          ["'", "'"],
+          ["\"", "\""],
+          ["`", "`"],
+          ["/", "/"],
+          ["<<'HERE'\n", "\nHERE"],
+          ["<<-HERE\n", "\nHERE"]
+        ].each do |opening, closing|
+          assert Prism.parse_success?("# encoding: shift_jis\n'\\\x82\xA0'\n")
+        end
+      end
+    end
+
+    private
+
+    def assert_encoding(encoding)
+      escapes = ["\\x00", "\\x7F", "\\x80", "\\xFF", "\\u{00}", "\\u{7F}", "\\u{80}", "\\M-\\C-?"]
+      escapes = escapes.concat(escapes.product(escapes).map(&:join))
+
+      escapes.each do |escaped|
+        source = "# encoding: #{encoding.name}\n\"#{escaped}\""
+
+        expected =
+          begin
+            eval(source).encoding
+          rescue SyntaxError => error
+            if error.message.include?("UTF-8 mixed within")
+              error.message[/UTF-8 mixed within .+? source/]
+            else
+              raise
+            end
+          end
+
+        actual =
+          Prism.parse(source).then do |result|
+            if result.success?
+              string = result.statement
+
+              if string.forced_utf8_encoding?
+                Encoding::UTF_8
+              elsif string.forced_binary_encoding?
+                Encoding::ASCII_8BIT
+              else
+                encoding
+              end
+            else
+              error = result.errors.first
+
+              if error.message.include?("mixed")
+                error.message
+              else
+                raise error.message
+              end
+            end
+          end
+
+        assert_equal expected, actual
+      end
+    end
+  end
+end

test/prism/encoding/symbol_encoding_test.rb

@@ -0,0 +1,108 @@
+# frozen_string_literal: true
+
+return if RUBY_ENGINE != "ruby"
+
+require_relative "../test_helper"
+
+module Prism
+  class SymbolEncodingTest < TestCase
+    each_encoding do |encoding, _|
+      define_method(:"test_symbols_#{encoding.name}") do
+        assert_symbols(encoding)
+      end
+
+      define_method(:"test_escapes_#{encoding.name}") do
+        assert_escapes(encoding)
+      end
+    end
+
+    private
+
+    def expected_encoding(source)
+      eval(source).encoding
+    end
+
+    def actual_encoding(source, encoding)
+      result = Prism.parse(source)
+
+      if result.success?
+        symbol = result.statement
+
+        if symbol.forced_utf8_encoding?
+          Encoding::UTF_8
+        elsif symbol.forced_binary_encoding?
+          Encoding::ASCII_8BIT
+        elsif symbol.forced_us_ascii_encoding?
+          Encoding::US_ASCII
+        else
+          encoding
+        end
+      else
+        raise SyntaxError.new(result.errors.map(&:message).join("\n"))
+      end
+    end
+
+    def assert_symbols(encoding)
+      [:a, :ą, :+].each do |symbol|
+        source = "# encoding: #{encoding.name}\n#{symbol.inspect}"
+
+        expected =
+          begin
+            expected_encoding(source)
+          rescue SyntaxError => error
+            if error.message.include?("invalid multibyte")
+              "invalid multibyte"
+            else
+              raise
+            end
+          end
+
+        actual =
+          begin
+            actual_encoding(source, encoding)
+          rescue SyntaxError => error
+            if error.message.include?("invalid multibyte")
+              "invalid multibyte"
+            else
+              raise
+            end
+          end
+
+        assert_equal expected, actual
+      end
+    end
+
+    def assert_escapes(encoding)
+      escapes = ["\\x00", "\\x7F", "\\x80", "\\xFF", "\\u{00}", "\\u{7F}", "\\u{80}", "\\M-\\C-?"]
+      escapes = escapes.concat(escapes.product(escapes).map(&:join))
+
+      escapes.each do |escaped|
+        source = "# encoding: #{encoding.name}\n:\"#{escaped}\""
+
+        expected =
+          begin
+            expected_encoding(source)
+          rescue SyntaxError => error
+            if error.message.include?("UTF-8 mixed within")
+              error.message[/UTF-8 mixed within .+? source/]
+            else
+              raise
+            end
+          end
+
+        actual =
+          begin
+            actual_encoding(source, encoding)
+          rescue SyntaxError => error
+            if error.message.include?("mixed")
+              error.message.split("\n", 2).first
+            else
+              raise
+            end
+          end
+
+        assert_equal expected, actual
+      end
+    end
+  end
+end

test/prism/encoding_test.rb

@@ -1,577 +0,0 @@
-# frozen_string_literal: true
-
-return if RUBY_ENGINE != "ruby"
-
-require_relative "test_helper"
-
-module Prism
-  class EncodingTest < TestCase
-    codepoints_1byte = 0...0x100
-    encodings = {
-      Encoding::ASCII_8BIT =>   codepoints_1byte,
-      Encoding::US_ASCII =>     codepoints_1byte
-    }
-
-    if !ENV["PRISM_BUILD_MINIMAL"]
-      encodings[Encoding::Windows_1253] = codepoints_1byte
-    end
-
-    # By default we don't test every codepoint in these encodings because it
-    # takes a very long time.
-    if ENV["PRISM_TEST_ALL_ENCODINGS"]
-      codepoints_2bytes = 0...0x10000
-      codepoints_unicode = (0...0x110000)
-
-      codepoints_eucjp = [
-        *(0...0x10000),
-        *(0...0x10000).map { |bytes| bytes | 0x8F0000 }
-      ]
-
-      codepoints_emacs_mule = [
-        *(0...0x80),
-        *((0x81...0x90).flat_map { |byte1| (0x90...0x100).map { |byte2| byte1 << 8 | byte2 } }),
-        *((0x90...0x9C).flat_map { |byte1| (0xA0...0x100).flat_map { |byte2| (0xA0...0x100).flat_map { |byte3| byte1 << 16 | byte2 << 8 | byte3 } } }),
-        *((0xF0...0xF5).flat_map { |byte2| (0xA0...0x100).flat_map { |byte3| (0xA0...0x100).flat_map { |byte4| 0x9C << 24 | byte3 << 16 | byte3 << 8 | byte4 } } }),
-      ]
-
-      codepoints_gb18030 = [
-        *(0...0x80),
-        *((0x81..0xFE).flat_map { |byte1| (0x40...0x100).map { |byte2| byte1 << 8 | byte2 } }),
-        *((0x81..0xFE).flat_map { |byte1| (0x30...0x40).flat_map { |byte2| (0x81..0xFE).flat_map { |byte3| (0x2F...0x41).map { |byte4| byte1 << 24 | byte2 << 16 | byte3 << 8 | byte4 } } } }),
-      ]
-
-      codepoints_euc_tw = [
-        *(0..0x7F),
-        *(0xA1..0xFF).flat_map { |byte1| (0xA1..0xFF).map { |byte2| (byte1 << 8) | byte2 } },
-        *(0xA1..0xB0).flat_map { |byte2| (0xA1..0xFF).flat_map { |byte3| (0xA1..0xFF).flat_map { |byte4| 0x8E << 24 | byte2 << 16 | byte3 << 8 | byte4 } } }
-      ]
-
-      encodings.merge!(
-        Encoding::CP850 =>                      codepoints_1byte,
-        Encoding::CP852 =>                      codepoints_1byte,
-        Encoding::CP855 =>                      codepoints_1byte,
-        Encoding::GB1988 =>                     codepoints_1byte,
-        Encoding::IBM437 =>                     codepoints_1byte,
-        Encoding::IBM720 =>                     codepoints_1byte,
-        Encoding::IBM737 =>                     codepoints_1byte,
-        Encoding::IBM775 =>                     codepoints_1byte,
-        Encoding::IBM852 =>                     codepoints_1byte,
-        Encoding::IBM855 =>                     codepoints_1byte,
-        Encoding::IBM857 =>                     codepoints_1byte,
-        Encoding::IBM860 =>                     codepoints_1byte,
-        Encoding::IBM861 =>                     codepoints_1byte,
-        Encoding::IBM862 =>                     codepoints_1byte,
-        Encoding::IBM863 =>                     codepoints_1byte,
-        Encoding::IBM864 =>                     codepoints_1byte,
-        Encoding::IBM865 =>                     codepoints_1byte,
-        Encoding::IBM866 =>                     codepoints_1byte,
-        Encoding::IBM869 =>                     codepoints_1byte,
-        Encoding::ISO_8859_1 =>                 codepoints_1byte,
-        Encoding::ISO_8859_2 =>                 codepoints_1byte,
-        Encoding::ISO_8859_3 =>                 codepoints_1byte,
-        Encoding::ISO_8859_4 =>                 codepoints_1byte,
-        Encoding::ISO_8859_5 =>                 codepoints_1byte,
-        Encoding::ISO_8859_6 =>                 codepoints_1byte,
-        Encoding::ISO_8859_7 =>                 codepoints_1byte,
-        Encoding::ISO_8859_8 =>                 codepoints_1byte,
-        Encoding::ISO_8859_9 =>                 codepoints_1byte,
-        Encoding::ISO_8859_10 =>                codepoints_1byte,
-        Encoding::ISO_8859_11 =>                codepoints_1byte,
-        Encoding::ISO_8859_13 =>                codepoints_1byte,
-        Encoding::ISO_8859_14 =>                codepoints_1byte,
-        Encoding::ISO_8859_15 =>                codepoints_1byte,
-        Encoding::ISO_8859_16 =>                codepoints_1byte,
-        Encoding::KOI8_R =>                     codepoints_1byte,
-        Encoding::KOI8_U =>                     codepoints_1byte,
-        Encoding::MACCENTEURO =>                codepoints_1byte,
-        Encoding::MACCROATIAN =>                codepoints_1byte,
-        Encoding::MACCYRILLIC =>                codepoints_1byte,
-        Encoding::MACGREEK =>                   codepoints_1byte,
-        Encoding::MACICELAND =>                 codepoints_1byte,
-        Encoding::MACROMAN =>                   codepoints_1byte,
-        Encoding::MACROMANIA =>                 codepoints_1byte,
-        Encoding::MACTHAI =>                    codepoints_1byte,
-        Encoding::MACTURKISH =>                 codepoints_1byte,
-        Encoding::MACUKRAINE =>                 codepoints_1byte,
-        Encoding::TIS_620 =>                    codepoints_1byte,
-        Encoding::Windows_1250 =>               codepoints_1byte,
-        Encoding::Windows_1251 =>               codepoints_1byte,
-        Encoding::Windows_1252 =>               codepoints_1byte,
-        Encoding::Windows_1254 =>               codepoints_1byte,
-        Encoding::Windows_1255 =>               codepoints_1byte,
-        Encoding::Windows_1256 =>               codepoints_1byte,
-        Encoding::Windows_1257 =>               codepoints_1byte,
-        Encoding::Windows_1258 =>               codepoints_1byte,
-        Encoding::Windows_874 =>                codepoints_1byte,
-        Encoding::Big5 =>                       codepoints_2bytes,
-        Encoding::Big5_HKSCS =>                 codepoints_2bytes,
-        Encoding::Big5_UAO =>                   codepoints_2bytes,
-        Encoding::CP949 =>                      codepoints_2bytes,
-        Encoding::CP950 =>                      codepoints_2bytes,
-        Encoding::CP951 =>                      codepoints_2bytes,
-        Encoding::EUC_KR =>                     codepoints_2bytes,
-        Encoding::GBK =>                        codepoints_2bytes,
-        Encoding::GB12345 =>                    codepoints_2bytes,
-        Encoding::GB2312 =>                     codepoints_2bytes,
-        Encoding::MACJAPANESE =>                codepoints_2bytes,
-        Encoding::Shift_JIS =>                  codepoints_2bytes,
-        Encoding::SJIS_DoCoMo =>                codepoints_2bytes,
-        Encoding::SJIS_KDDI =>                  codepoints_2bytes,
-        Encoding::SJIS_SoftBank =>              codepoints_2bytes,
-        Encoding::Windows_31J =>                codepoints_2bytes,
-        Encoding::UTF_8 =>                      codepoints_unicode,
-        Encoding::UTF8_MAC =>                   codepoints_unicode,
-        Encoding::UTF8_DoCoMo =>                codepoints_unicode,
-        Encoding::UTF8_KDDI =>                  codepoints_unicode,
-        Encoding::UTF8_SoftBank =>              codepoints_unicode,
-        Encoding::CESU_8 =>                     codepoints_unicode,
-        Encoding::CP51932 =>                    codepoints_eucjp,
-        Encoding::EUC_JP =>                     codepoints_eucjp,
-        Encoding::EUCJP_MS =>                   codepoints_eucjp,
-        Encoding::EUC_JIS_2004 =>               codepoints_eucjp,
-        Encoding::EMACS_MULE =>                 codepoints_emacs_mule,
-        Encoding::STATELESS_ISO_2022_JP =>      codepoints_emacs_mule,
-        Encoding::STATELESS_ISO_2022_JP_KDDI => codepoints_emacs_mule,
-        Encoding::GB18030 =>                    codepoints_gb18030,
-        Encoding::EUC_TW =>                     codepoints_euc_tw
-      )
-    end
-
-    # These test that we're correctly parsing codepoints for each alias of each
-    # encoding that prism supports.
-    encodings.each do |encoding, range|
-      (encoding.names - %w[external internal filesystem locale]).each do |name|
-        define_method(:"test_encoding_#{name}") do
-          assert_encoding(encoding, name, range)
-        end
-      end
-    end
-
-    # These test that we're correctly setting the flags on strings for each
-    # encoding that prism supports.
-    escapes = ["\\x00", "\\x7F", "\\x80", "\\xFF", "\\u{00}", "\\u{7F}", "\\u{80}", "\\M-\\C-?"]
-    escapes = escapes.concat(escapes.product(escapes).map(&:join))
-    symbols = [:a, :ą, :+]
-    regexps = [/a/, /ą/, //]
-
-    encodings.each_key do |encoding|
-      define_method(:"test_encoding_flags_#{encoding.name}") do
-        assert_encoding_flags(encoding, escapes)
-      end
-
-      define_method(:"test_symbol_encoding_flags_#{encoding.name}") do
-        assert_symbol_encoding_flags(encoding, symbols)
-      end
-
-      define_method(:"test_symbol_character_escape_encoding_flags_#{encoding.name}") do
-        assert_symbol_character_escape_encoding_flags(encoding, escapes)
-      end
-
-      define_method(:"test_regular_expression_encoding_flags_#{encoding.name}") do
-        assert_regular_expression_encoding_flags(encoding, regexps.map(&:inspect))
-      end
-
-      define_method(:"test_regular_expression_escape_encoding_flags_#{encoding.name}") do
-        assert_regular_expression_encoding_flags(encoding, escapes.map { |e| "/#{e}/" })
-      end
-    end
-
-    encoding_modifiers = { ascii_8bit: "n", utf_8: "u", euc_jp: "e", windows_31j: "s" }
-    regexp_sources = ["abc", "garçon", "\\x80", "gar\\xC3\\xA7on", "gar\\u{E7}on", "abc\\u{FFFFFF}", "\\x80\\u{80}" ]
-
-    encoding_modifiers.each_value do |modifier|
-      encodings.each_key do |encoding|
-        define_method(:"test_regular_expression_encoding_modifiers_/#{modifier}_#{encoding.name}") do
-          assert_regular_expression_encoding_flags(
-            encoding,
-            regexp_sources.product(encoding_modifiers.values).map { |r, modifier| "/#{r}/#{modifier}" }
-          )
-        end
-      end
-    end
-
-    def test_coding
-      result = Prism.parse("# coding: utf-8\n'string'")
-      actual = result.value.statements.body.first.unescaped.encoding
-      assert_equal Encoding.find("utf-8"), actual
-    end
-
-    def test_coding_with_whitespace
-      result = Prism.parse("# coding \t \r  \v   :     \t \v    \r   ascii-8bit \n'string'")
-      actual = result.value.statements.body.first.unescaped.encoding
-      assert_equal Encoding.find("ascii-8bit"), actual
-    end
-
-    def test_emacs_style
-      result = Prism.parse("# -*- coding: utf-8 -*-\n'string'")
-      actual = result.value.statements.body.first.unescaped.encoding
-      assert_equal Encoding.find("utf-8"), actual
-    end
-
-    def test_utf_8_variations
-      %w[
-        utf-8-unix
-        utf-8-dos
-        utf-8-mac
-        utf-8-*
-      ].each do |encoding|
-        result = Prism.parse("# coding: #{encoding}\n'string'")
-        actual = result.value.statements.body.first.unescaped.encoding
-        assert_equal Encoding.find("utf-8"), actual
-      end
-    end
-
-    def test_first_lexed_token
-      encoding = Prism.lex("# encoding: ascii-8bit").value[0][0].value.encoding
-      assert_equal Encoding.find("ascii-8bit"), encoding
-    end
-
-    if !ENV["PRISM_BUILD_MINIMAL"]
-      # This test may be a little confusing. Basically when we use our strpbrk,
-      # it takes into account the encoding of the file.
-      def test_strpbrk_multibyte
-        result = Prism.parse(<<~RUBY)
-          # encoding: Shift_JIS
-          %w[\x81\x5c]
-        RUBY
-
-        assert(result.errors.empty?)
-        assert_equal(
-          (+"\x81\x5c").force_encoding(Encoding::Shift_JIS),
-          result.value.statements.body.first.elements.first.unescaped
-        )
-      end
-
-      def test_slice_encoding
-        slice = Prism.parse("# encoding: Shift_JIS\nア").value.slice
-        assert_equal (+"ア").force_encoding(Encoding::SHIFT_JIS), slice
-        assert_equal Encoding::SHIFT_JIS, slice.encoding
-      end
-
-      def test_multibyte_escapes
-        [
-          ["'", "'"],
-          ["\"", "\""],
-          ["`", "`"],
-          ["/", "/"],
-          ["<<'HERE'\n", "\nHERE"],
-          ["<<-HERE\n", "\nHERE"]
-        ].each do |opening, closing|
-          assert Prism.parse_success?("# encoding: shift_jis\n'\\\x82\xA0'\n")
-        end
-      end
-    end
-
-    private
-
-    class ConstantContext < BasicObject
-      def self.const_missing(const)
-        const
-      end
-    end
-
-    def constant_context
-      ConstantContext.new
-    end
-
-    class IdentifierContext < BasicObject
-      def method_missing(name, *)
-        name
-      end
-    end
-
-    def identifier_context
-      IdentifierContext.new
-    end
-
-    def assert_encoding_constant(name, character)
-      source = "# encoding: #{name}\n#{character}"
-      expected = constant_context.instance_eval(source)
-
-      result = Prism.parse(source)
-      assert result.success?
-
-      actual = result.value.statements.body.last
-      assert_kind_of ConstantReadNode, actual
-      assert_equal expected, actual.name
-    end
-
-    def assert_encoding_identifier(name, character)
-      source = "# encoding: #{name}\n#{character}"
-      expected = identifier_context.instance_eval(source)
-
-      result = Prism.parse(source)
-      assert result.success?
-
-      actual = result.value.statements.body.last
-      assert_kind_of CallNode, actual
-      assert_equal expected, actual.name
-    end
-
-    # Check that we can properly parse every codepoint in the given encoding.
-    def assert_encoding(encoding, name, range)
-      # I'm not entirely sure, but I believe these codepoints are incorrect in
-      # their parsing in CRuby. They all report as matching `[[:lower:]]` but
-      # then they are parsed as constants. This is because CRuby determines if
-      # an identifier is a constant or not by case folding it down to lowercase
-      # and checking if there is a difference. And even though they report
-      # themselves as lowercase, their case fold is different. I have reported
-      # this bug upstream.
-      case encoding
-      when Encoding::UTF_8, Encoding::UTF_8_MAC, Encoding::UTF8_DoCoMo, Encoding::UTF8_KDDI, Encoding::UTF8_SoftBank, Encoding::CESU_8
-        range = range.to_a - [
-          0x01c5, 0x01c8, 0x01cb, 0x01f2, 0x1f88, 0x1f89, 0x1f8a, 0x1f8b,
-          0x1f8c, 0x1f8d, 0x1f8e, 0x1f8f, 0x1f98, 0x1f99, 0x1f9a, 0x1f9b,
-          0x1f9c, 0x1f9d, 0x1f9e, 0x1f9f, 0x1fa8, 0x1fa9, 0x1faa, 0x1fab,
-          0x1fac, 0x1fad, 0x1fae, 0x1faf, 0x1fbc, 0x1fcc, 0x1ffc,
-        ]
-      when Encoding::Windows_1253
-        range = range.to_a - [0xb5]
-      end
-
-      range.each do |codepoint|
-        character = codepoint.chr(encoding)
-
-        if character.match?(/[[:alpha:]]/)
-          if character.match?(/[[:upper:]]/)
-            assert_encoding_constant(name, character)
-          else
-            assert_encoding_identifier(name, character)
-          end
-        elsif character.match?(/[[:alnum:]]/)
-          assert_encoding_identifier(name, "_#{character}")
-        else
-          next if ["/", "{"].include?(character)
-
-          source = "# encoding: #{name}\n/(?##{character})/\n"
-          assert Prism.parse(source).success?, "Expected #{source.inspect} to parse successfully."
-        end
-      rescue RangeError
-        source = "# encoding: #{name}\n\\x#{codepoint.to_s(16)}"
-        refute Prism.parse(source).success?
-      end
-    end
-
-    def assert_encoding_flags(encoding, escapes)
-      escapes.each do |escaped|
-        source = "# encoding: #{encoding.name}\n\"#{escaped}\""
-
-        expected =
-          begin
-            eval(source).encoding
-          rescue SyntaxError => error
-            if error.message.include?("UTF-8 mixed within")
-              error.message[/: (.+?)\n/, 1]
-            else
-              raise
-            end
-          end
-
-        actual =
-          Prism.parse(source).then do |result|
-            if result.success?
-              string = result.value.statements.body.first
-
-              if string.forced_utf8_encoding?
-                Encoding::UTF_8
-              elsif string.forced_binary_encoding?
-                Encoding::ASCII_8BIT
-              else
-                encoding
-              end
-            else
-              error = result.errors.first
-
-              if error.message.include?("mixed")
-                error.message
-              else
-                raise error.message
-              end
-            end
-          end
-
-        assert_equal expected, actual
-      end
-    end
-
-    # Test Symbol literals without any interpolation or escape sequences.
-    def assert_symbol_encoding_flags(encoding, symbols)
-      symbols.each do |symbol|
-        source = "# encoding: #{encoding.name}\n#{symbol.inspect}"
-
-        expected =
-          begin
-            eval(source).encoding
-          rescue SyntaxError => error
-            unless error.message.include?("invalid multibyte char")
-              raise
-            end
-          end
-
-        actual =
-          Prism.parse(source).then do |result|
-            if result.success?
-              symbol = result.value.statements.body.first
-
-              if symbol.forced_utf8_encoding?
-                Encoding::UTF_8
-              elsif symbol.forced_binary_encoding?
-                Encoding::ASCII_8BIT
-              elsif symbol.forced_us_ascii_encoding?
-                Encoding::US_ASCII
-              else
-                encoding
-              end
-            else
-              error = result.errors.last
-
-              unless error.message.include?("invalid symbol")
-                raise error.message
-              end
-            end
-          end
-
-        assert_equal expected, actual
-      end
-    end
-
-    def assert_symbol_character_escape_encoding_flags(encoding, escapes)
-      escapes.each do |escaped|
-        source = "# encoding: #{encoding.name}\n:\"#{escaped}\""
-
-        expected =
-          begin
-            eval(source).encoding
-          rescue SyntaxError => error
-            if error.message.include?("UTF-8 mixed within")
-              error.message[/: (.+?)\n/, 1]
-            else
-              raise
-            end
-          end
-
-        actual =
-          Prism.parse(source).then do |result|
-            if result.success?
-              symbol = result.value.statements.body.first
-
-              if symbol.forced_utf8_encoding?
-                Encoding::UTF_8
-              elsif symbol.forced_binary_encoding?
-                Encoding::ASCII_8BIT
-              elsif symbol.forced_us_ascii_encoding?
-                Encoding::US_ASCII
-              else
-                encoding
-              end
-            else
-              error = result.errors.first
-
-              if error.message.include?("mixed")
-                error.message
-              else
-                raise error.message
-              end
-            end
-          end
-
-        assert_equal expected, actual
-      end
-    end
-
-    def assert_regular_expression_encoding_flags(encoding, regexps)
-      regexps.each do |regexp|
-        regexp_modifier_used = regexp.end_with?("/u") || regexp.end_with?("/e") || regexp.end_with?("/s") || regexp.end_with?("/n")
-        source = "# encoding: #{encoding.name}\n#{regexp}"
-
-        encoding_errors = ["invalid multibyte char", "escaped non ASCII character in UTF-8 regexp", "differs from source encoding"]
-        skipped_errors = ["invalid multibyte escape", "incompatible character encoding", "UTF-8 character in non UTF-8 regexp", "invalid Unicode range", "invalid Unicode list"]
-
-        # TODO (nirvdrum 21-Feb-2024): Prism currently does not handle Regexp validation unless modifiers are used. So, skip processing those errors for now: https://github.com/ruby/prism/issues/2104
-        unless regexp_modifier_used
-          skipped_errors += encoding_errors
-          encoding_errors.clear
-        end
-
-        expected =
-          begin
-            eval(source).encoding
-          rescue SyntaxError => error
-            if encoding_errors.find { |e| error.message.include?(e) }
-              error.message.split("\n").map { |m| m[/: (.+?)$/, 1] }
-            elsif skipped_errors.find { |e| error.message.include?(e) }
-              next
-            else
-              raise
-            end
-          end
-
-        actual =
-          Prism.parse(source).then do |result|
-            if result.success?
-              regexp = result.value.statements.body.first
-
-              actual_encoding = if regexp.forced_utf8_encoding?
-                Encoding::UTF_8
-              elsif regexp.forced_binary_encoding?
-                Encoding::ASCII_8BIT
-              elsif regexp.forced_us_ascii_encoding?
-                Encoding::US_ASCII
-              elsif regexp.ascii_8bit?
-                Encoding::ASCII_8BIT
-              elsif regexp.utf_8?
-                Encoding::UTF_8
-              elsif regexp.euc_jp?
-                Encoding::EUC_JP
-              elsif regexp.windows_31j?
-                Encoding::Windows_31J
-              else
-                encoding
-              end
-
-              if regexp.utf_8? && actual_encoding != Encoding::UTF_8
-                raise "expected regexp encoding to be UTF-8 due to '/u' modifier, but got #{actual_encoding.name}"
-              elsif regexp.ascii_8bit? && (actual_encoding != Encoding::ASCII_8BIT && actual_encoding != Encoding::US_ASCII)
-                raise "expected regexp encoding to be ASCII-8BIT or US-ASCII due to '/n' modifier, but got #{actual_encoding.name}"
-              elsif regexp.euc_jp? && actual_encoding != Encoding::EUC_JP
-                raise "expected regexp encoding to be EUC-JP due to '/e' modifier, but got #{actual_encoding.name}"
-              elsif regexp.windows_31j? && actual_encoding != Encoding::Windows_31J
-                raise "expected regexp encoding to be Windows-31J due to '/s' modifier, but got #{actual_encoding.name}"
-              end
-
-              if regexp.utf_8? && regexp.forced_utf8_encoding?
-                raise "the forced_utf8 flag should not be set when the UTF-8 modifier (/u) is used"
-              elsif regexp.ascii_8bit? && regexp.forced_binary_encoding?
-                raise "the forced_ascii_8bit flag should not be set when the UTF-8 modifier (/u) is used"
-              end
-
-              actual_encoding
-            else
-              errors = result.errors.map(&:message)
-
-              if errors.last&.include?("UTF-8 mixed within")
-                nil
-              else
-                errors
-              end
-            end
-          end
-
-        # TODO (nirvdrum 22-Feb-2024): Remove this workaround once Prism better maps CRuby's error messages.
-        # This class of error message is tricky. The part not being compared is a representation of the regexp.
-        # Depending on the source encoding and any encoding modifiers being used, CRuby alters how the regexp is represented.
-        # Sometimes it's an MBC string. Other times it uses hexadecimal character escapes. And in other cases it uses
-        # the long-form Unicode escape sequences. This short-circuit checks that the error message is mostly correct.
-        if expected.is_a?(Array) && actual.is_a?(Array)
-          if expected.last.start_with?("/.../n has a non escaped non ASCII character in non ASCII-8BIT script:") &&
-              actual.last.start_with?("/.../n has a non escaped non ASCII character in non ASCII-8BIT script:")
-              expected.last.clear
-              actual.last.clear
-          end
-        end
-
-        assert_equal expected, actual
-      end
-    end
-  end
-end

test/prism/errors_test.rb

@@ -1246,8 +1246,7 @@ module Prism
     end
 
     def test_invalid_message_name
-      result = Prism.parse("+.@foo,+=foo")
-      assert_equal :"", result.value.statements.body.first.write_name
+      assert_equal :"", Prism.parse_statement("+.@foo,+=foo").write_name
     end
 
     def test_invalid_operator_write_fcall

test/prism/fixtures_test.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+return if RUBY_VERSION < "3.2.0"
+
+require_relative "test_helper"
+
+module Prism
+  class FixturesTest < TestCase
+    except = []
+
+    # Ruby < 3.3.0 cannot parse heredocs where there are leading whitespace
+    # characters in the heredoc start.
+    # Example: <<~'   EOF' or <<-'  EOF'
+    # https://bugs.ruby-lang.org/issues/19539
+    except << "heredocs_leading_whitespace.txt" if RUBY_VERSION < "3.3.0"
+
+    Fixture.each(except: except) do |fixture|
+      define_method(fixture.test_name) { assert_valid_syntax(fixture.read) }
+    end
+  end
+end

test/prism/fuzzer_test.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-return if ENV["PRISM_BUILD_MINIMAL"]
-
 require_relative "test_helper"
 
 module Prism
@@ -9,7 +7,7 @@ module Prism
   # invalid memory access.
   class FuzzerTest < TestCase
     def self.snippet(name, source)
-      define_method(:"test_fuzzer_#{name}") { Prism.dump(source) }
+      define_method(:"test_fuzzer_#{name}") { Prism.profile(source) }
     end
 
     snippet "incomplete global variable", "$"
@@ -39,29 +37,31 @@ module Prism
     snippet "escaped unicode at end of file 8", '"\\u33'
     snippet "escaped unicode at end of file 9", '"\\u333'
     snippet "float suffix at end of file", "1e"
+    snippet "parameter name that is zero length", "a { |b;"
 
     snippet "statements node with multiple heredocs", <<~EOF
       for <<A + <<B
       A
       B
     EOF
+
     snippet "create a binary call node with arg before receiver", <<~EOF
       <<-A.g/{/
       A
       /, ""\\
     EOF
+
     snippet "regular expression with start and end out of order", <<~RUBY
       <<-A.g//,
       A
       /{/, ''\\
     RUBY
+
     snippet "interpolated regular expression with start and end out of order", <<~RUBY
       <<-A.g/{/,
       A
       a
       /{/, ''\\
     RUBY
-
-    snippet "parameter name that is zero length", "a { |b;"
   end
 end

test/prism/heredoc_dedent_test.rb

@@ -4,15 +4,122 @@ require_relative "test_helper"
 
 module Prism
   class HeredocDedentTest < TestCase
-    filepath = File.expand_path("fixtures/tilde_heredocs.txt", __dir__)
+    def test_content_dedented_interpolation_content
+      assert_heredoc_dedent(
+        "  a\n" "1\n" "  a\n",
+        "<<~EOF\n" "  a\n" "\#{1}\n" "  a\n" "EOF\n"
+      )
+    end
 
-    File.read(filepath).split(/(?=\n)\n(?=<)/).each_with_index do |heredoc, index|
-      # The first example in this file has incorrect dedent calculated by
-      # TruffleRuby so we skip it.
-      next if index == 0 && RUBY_ENGINE == "truffleruby"
+    def test_content
+      assert_heredoc_dedent(
+        "a\n",
+        "<<~EOF\n" "  a\n" "EOF\n"
+      )
+    end
 
-      define_method "test_heredoc_#{index}" do
-        node = Prism.parse(heredoc).value.statements.body.first
+    def test_tabs_dedent_spaces
+      assert_heredoc_dedent(
+        "\ta\n" "b\n" "\t\tc\n",
+        "<<~EOF\n" "\ta\n" "  b\n" "\t\tc\n" "EOF\n"
+      )
+    end
+
+    def test_interpolation_then_content
+      assert_heredoc_dedent(
+        "1 a\n",
+        "<<~EOF\n" "  \#{1} a\n" "EOF\n"
+      )
+    end
+
+    def test_content_then_interpolation
+      assert_heredoc_dedent(
+        "a 1\n",
+        "<<~EOF\n" "  a \#{1}\n" "EOF\n"
+      )
+    end
+
+    def test_content_dedented_interpolation
+      assert_heredoc_dedent(
+        " a\n" "1\n",
+        "<<~EOF\n" "  a\n" " \#{1}\n" "EOF\n"
+      )
+    end
+
+    def test_content_interpolation
+      assert_heredoc_dedent(
+        "a\n" "1\n",
+        "<<~EOF\n" "  a\n" "  \#{1}\n" "EOF\n"
+      )
+    end
+
+    def test_content_content
+      assert_heredoc_dedent(
+        "a\n" "b\n",
+        "<<~EOF\n" "  a\n" "  b\n" "EOF\n"
+      )
+    end
+
+    def test_content_indented_content
+      assert_heredoc_dedent(
+        "a\n" "  b\n",
+        "<<~EOF\n" "  a\n" "    b\n" "EOF\n"
+      )
+    end
+
+    def test_content_dedented_content
+      assert_heredoc_dedent(
+        "\ta\n" "b\n",
+        "<<~EOF\n" "\t\t\ta\n" "\t\tb\n" "EOF\n"
+      )
+    end
+
+    def test_single_quote
+      assert_heredoc_dedent(
+        "a \#{1}\n",
+        "<<~'EOF'\n" "a \#{1}\n" "EOF\n"
+      )
+    end
+
+    def test_mixed_indentation
+      assert_heredoc_dedent(
+        "a\n" " b\n",
+        "<<~EOF\n" "\ta\n" "\t b\n" "EOF\n"
+      )
+    end
+
+    def test_indented_content_content
+      assert_heredoc_dedent(
+        " a\n" "b\n",
+        "<<~EOF\n" "\t a\n" "\tb\n" "EOF\n"
+      )
+    end
+
+    def test_indent_size
+      assert_heredoc_dedent(
+        "a\n" "  b\n",
+        "<<~EOF\n" "\ta\n" "          b\n" "EOF\n"
+      )
+    end
+
+    def test_blank_lines
+      assert_heredoc_dedent(
+        "a\n" "\n" "b\n",
+        "<<~EOF\n" "  a\n" "\n" "  b\n" "EOF\n"
+      )
+    end
+
+    def test_many_blank_lines
+      assert_heredoc_dedent(
+        "a\n" "\n" "\n" "\n" "\n" "b\n",
+        "<<~EOF\n" "  a\n" "\n" "\n" "\n" "\n" "  b\n" "EOF\n"
+      )
+    end
+
+    private
+
+    def assert_heredoc_dedent(expected, source)
+      node = Prism.parse_statement(source)
 
       if node.is_a?(StringNode)
         actual = node.unescaped
@@ -20,8 +127,8 @@ module Prism
         actual = node.parts.map { |part| part.is_a?(StringNode) ? part.unescaped : "1" }.join
       end
 
-        assert_equal(eval(heredoc), actual, "Expected heredocs to match.")
-      end
+      assert_equal(expected, actual)
+      assert_equal(eval(source), actual)
     end
   end
 end

test/prism/lex_test.rb

@@ -0,0 +1,90 @@
+# frozen_string_literal: true
+
+return if !(RUBY_ENGINE == "ruby" && RUBY_VERSION >= "3.2.0")
+
+require_relative "test_helper"
+
+module Prism
+  class LexTest < TestCase
+    except = [
+      # It seems like there are some oddities with nested heredocs and ripper.
+      # Waiting for feedback on https://bugs.ruby-lang.org/issues/19838.
+      "seattlerb/heredoc_nested.txt",
+      "whitequark/dedenting_heredoc.txt",
+      # Ripper seems to have a bug that the regex portions before and after
+      # the heredoc are combined into a single token. See
+      # https://bugs.ruby-lang.org/issues/19838.
+      "spanning_heredoc.txt",
+      "spanning_heredoc_newlines.txt"
+    ]
+
+    if RUBY_VERSION < "3.3.0"
+      # This file has changed behavior in Ripper in Ruby 3.3, so we skip it if
+      # we're on an earlier version.
+      except << "seattlerb/pct_w_heredoc_interp_nested.txt"
+
+      # Ruby < 3.3.0 cannot parse heredocs where there are leading whitespace
+      # characters in the heredoc start.
+      # Example: <<~'   EOF' or <<-'  EOF'
+      # https://bugs.ruby-lang.org/issues/19539
+      except << "heredocs_leading_whitespace.txt"
+    end
+
+    Fixture.each(except: except) do |fixture|
+      define_method(fixture.test_name) { assert_lex(fixture) }
+    end
+
+    def test_lex_file
+      assert_nothing_raised do
+        Prism.lex_file(__FILE__)
+      end
+
+      error = assert_raise Errno::ENOENT do
+        Prism.lex_file("idontexist.rb")
+      end
+
+      assert_equal "No such file or directory - idontexist.rb", error.message
+
+      assert_raise TypeError do
+        Prism.lex_file(nil)
+      end
+    end
+
+    def test_parse_lex
+      node, tokens = Prism.parse_lex("def foo; end").value
+
+      assert_kind_of ProgramNode, node
+      assert_equal 5, tokens.length
+    end
+
+    def test_parse_lex_file
+      node, tokens = Prism.parse_lex_file(__FILE__).value
+
+      assert_kind_of ProgramNode, node
+      refute_empty tokens
+
+      error = assert_raise Errno::ENOENT do
+        Prism.parse_lex_file("idontexist.rb")
+      end
+
+      assert_equal "No such file or directory - idontexist.rb", error.message
+
+      assert_raise TypeError do
+        Prism.parse_lex_file(nil)
+      end
+    end
+
+    private
+
+    def assert_lex(fixture)
+      source = fixture.read
+
+      result = Prism.lex_compat(source)
+      assert_equal [], result.errors
+
+      Prism.lex_ripper(source).zip(result.value).each do |(ripper, prism)|
+        assert_equal ripper, prism
+      end
+    end
+  end
+end

test/prism/library_symbols_test.rb

@@ -3,8 +3,6 @@
 require_relative "test_helper"
 
 return if RUBY_PLATFORM !~ /linux/
-
-# TODO: determine why these symbols are incorrect on ppc64le
 return if RUBY_PLATFORM =~ /powerpc64le/
 
 module Prism

test/prism/locals_test.rb

@@ -17,14 +17,14 @@ require_relative "test_helper"
 
 module Prism
   class LocalsTest < TestCase
-    base = File.join(__dir__, "fixtures")
-    Dir["**/*.txt", base: base].each do |relative|
+    except = [
       # Skip this fixture because it has a different number of locals because
       # CRuby is eliminating dead code.
-      next if relative == "whitequark/ruby_bug_10653.txt"
+      "whitequark/ruby_bug_10653.txt"
+    ]
 
-      filepath = File.join(base, relative)
-      define_method("test_#{relative}") { assert_locals(filepath) }
+    Fixture.each(except: except) do |fixture|
+      define_method(fixture.test_name) { assert_locals(fixture) }
     end
 
     def setup
@@ -38,8 +38,8 @@ module Prism
 
     private
 
-    def assert_locals(filepath)
-      source = File.read(filepath)
+    def assert_locals(fixture)
+      source = fixture.read
 
       expected = cruby_locals(source)
       actual = prism_locals(source)
@@ -47,14 +47,6 @@ module Prism
       assert_equal(expected, actual)
     end
 
-    def ignore_warnings
-      previous_verbosity = $VERBOSE
-      $VERBOSE = nil
-      yield
-    ensure
-      $VERBOSE = previous_verbosity
-    end
-
     # A wrapper around a RubyVM::InstructionSequence that provides a more
     # convenient interface for accessing parts of the iseq.
     class ISeq
@@ -104,11 +96,8 @@ module Prism
     # For the given source, compiles with CRuby and returns a list of all of the
     # sets of local variables that were encountered.
     def cruby_locals(source)
-      verbose, $VERBOSE = $VERBOSE, nil
-
-      begin
       locals = [] #: Array[Array[Symbol | Integer]]
-        stack = [ISeq.new(RubyVM::InstructionSequence.compile(source).to_a)]
+      stack = [ISeq.new(ignore_warnings { RubyVM::InstructionSequence.compile(source) }.to_a)]
 
       while (iseq = stack.pop)
         names = [*iseq.local_table]
@@ -130,9 +119,6 @@ module Prism
       end
 
       locals
-      ensure
-        $VERBOSE = verbose
-      end
     end
 
     # For the given source, parses with prism and returns a list of all of the

test/prism/magic_comment_test.rb

@@ -2,32 +2,109 @@
 
 require_relative "test_helper"
 
-return if RUBY_ENGINE != "ruby"
-
 module Prism
   class MagicCommentTest < TestCase
-    examples = [
-      "# encoding: ascii",
-      "# coding: ascii",
-      "# eNcOdInG: ascii",
-      "# CoDiNg: ascii",
-      "# \s\t\v encoding \s\t\v : \s\t\v ascii \s\t\v",
-      "# -*- encoding: ascii -*-",
-      "# -*- coding: ascii -*-",
-      "# -*- eNcOdInG: ascii -*-",
-      "# -*- CoDiNg: ascii -*-",
-      "# -*- \s\t\v encoding \s\t\v : \s\t\v ascii \s\t\v -*-",
-      "# -*- foo: bar; encoding: ascii -*-",
-      "# coding \t \r  \v   :     \t \v    \r   ascii-8bit",
-      "# vim: filetype=ruby, fileencoding=windows-31j, tabsize=3, shiftwidth=3"
-    ]
+    if RUBY_ENGINE == "ruby"
+      class MagicCommentRipper < Ripper
+        attr_reader :magic_comments
 
-    examples.each.with_index(1) do |example, index|
-      define_method(:"test_magic_comment_#{index}") do
-        expected = RubyVM::InstructionSequence.compile(%Q{#{example}\n""}).eval.encoding
-        actual = Prism.parse(example).encoding
+        def initialize(*)
+          super
+          @magic_comments = []
+        end
+
+        def on_magic_comment(key, value)
+          @magic_comments << [key, value]
+          super
+        end
+      end
+
+      Fixture.each do |fixture|
+        define_method(fixture.test_name) { assert_magic_comments(fixture) }
+      end
+    end
+
+    def test_encoding
+      assert_magic_encoding(Encoding::US_ASCII, "# encoding: ascii")
+    end
+
+    def test_coding
+      assert_magic_encoding(Encoding::US_ASCII, "# coding: ascii")
+    end
+
+    def test_eNcOdInG
+      assert_magic_encoding(Encoding::US_ASCII, "# eNcOdInG: ascii")
+    end
+
+    def test_CoDiNg
+      assert_magic_encoding(Encoding::US_ASCII, "# CoDiNg: ascii")
+    end
+
+    def test_encoding_whitespace
+      assert_magic_encoding(Encoding::US_ASCII, "# \s\t\v encoding \s\t\v : \s\t\v ascii \s\t\v")
+    end
+
+    def test_emacs_encoding
+      assert_magic_encoding(Encoding::US_ASCII, "# -*- encoding: ascii -*-")
+    end
+
+    def test_emacs_coding
+      assert_magic_encoding(Encoding::US_ASCII, "# -*- coding: ascii -*-")
+    end
+
+    def test_emacs_eNcOdInG
+      assert_magic_encoding(Encoding::US_ASCII, "# -*- eNcOdInG: ascii -*-")
+    end
+
+    def test_emacs_CoDiNg
+      assert_magic_encoding(Encoding::US_ASCII, "# -*- CoDiNg: ascii -*-")
+    end
+
+    def test_emacs_whitespace
+      assert_magic_encoding(Encoding::US_ASCII, "# -*- \s\t\v encoding \s\t\v : \s\t\v ascii \s\t\v -*-")
+    end
+
+    def test_emacs_multiple
+      assert_magic_encoding(Encoding::US_ASCII, "# -*- foo: bar; encoding: ascii -*-")
+    end
+
+    def test_coding_whitespace
+      assert_magic_encoding(Encoding::ASCII_8BIT, "# coding \t \r  \v   :     \t \v    \r   ascii-8bit")
+    end
+
+    def test_vim
+      assert_magic_encoding(Encoding::Windows_31J, "# vim: filetype=ruby, fileencoding=windows-31j, tabsize=3, shiftwidth=3")
+    end
+
+    private
+
+    def assert_magic_encoding(expected, line)
+      source = %Q{#{line}\n""}
+      actual = Prism.parse(source).encoding
+
+      # Compare against our expectation.
+      assert_equal expected, actual
+
+      # Compare against Ruby's expectation.
+      if defined?(RubyVM::InstructionSequence)
+        expected = RubyVM::InstructionSequence.compile(source).eval.encoding
         assert_equal expected, actual
       end
     end
+
+    def assert_magic_comments(fixture)
+      source = fixture.read
+
+      # Check that we get the correct number of magic comments when lexing with
+      # ripper.
+      expected = MagicCommentRipper.new(source).tap(&:parse).magic_comments
+      actual = Prism.parse(source).magic_comments
+
+      assert_equal expected.length, actual.length
+      expected.zip(actual).each do |(expected_key, expected_value), magic_comment|
+        assert_equal expected_key, magic_comment.key
+        assert_equal expected_value, magic_comment.value
+      end
+    end
   end
 end

test/prism/newline_offsets_test.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require_relative "test_helper"
+
+module Prism
+  class NewlineOffsetsTest < TestCase
+    Fixture.each do |fixture|
+      define_method(fixture.test_name) { assert_newline_offsets(fixture) }
+    end
+
+    private
+
+    def assert_newline_offsets(fixture)
+      source = fixture.read
+
+      expected = [0]
+      source.b.scan("\n") { expected << $~.offset(0)[0] + 1 }
+
+      assert_equal expected, Prism.parse(source).source.offsets
+    end
+  end
+end

test/prism/newline_test.rb

@@ -6,20 +6,23 @@ return unless defined?(RubyVM::InstructionSequence)
 
 module Prism
   class NewlineTest < TestCase
-    base = File.expand_path("../", __FILE__)
-    filepaths = Dir["*.rb", base: base] - %w[
-      encoding_test.rb
+    skips = %w[
       errors_test.rb
       locals_test.rb
-      parser_test.rb
       regexp_test.rb
-      static_literals_test.rb
+      test_helper.rb
       unescape_test.rb
-      warnings_test.rb
+      encoding/regular_expression_encoding_test.rb
+      encoding/string_encoding_test.rb
+      result/static_literals_test.rb
+      result/warnings_test.rb
+      ruby/parser_test.rb
+      ruby/ruby_parser_test.rb
     ]
 
-    filepaths.each do |relative|
-      define_method("test_newline_flags_#{relative}") do
+    base = __dir__
+    (Dir["{,api/,encoding/,result/,ruby/}*.rb", base: base] - skips).each do |relative|
+      define_method(:"test_#{relative}") do
         assert_newlines(base, relative)
       end
     end
@@ -65,14 +68,6 @@ module Prism
       assert_equal expected, actual
     end
 
-    def ignore_warnings
-      previous_verbosity = $VERBOSE
-      $VERBOSE = nil
-      yield
-    ensure
-      $VERBOSE = previous_verbosity
-    end
-
     def rubyvm_lines(source)
       queue = [ignore_warnings { RubyVM::InstructionSequence.compile(source) }]
       lines = []

test/prism/parse_test.rb

@@ -1,371 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "test_helper"
-
-module Prism
-  class ParseTest < TestCase
-    # A subclass of Ripper that extracts out magic comments.
-    class MagicCommentRipper < Ripper
-      attr_reader :magic_comments
-
-      def initialize(*)
-        super
-        @magic_comments = []
-      end
-
-      def on_magic_comment(key, value)
-        @magic_comments << [key, value]
-        super
-      end
-    end
-
-    # When we pretty-print the trees to compare against the snapshots, we want to
-    # be certain that we print with the same external encoding. This is because
-    # methods like Symbol#inspect take into account external encoding and it could
-    # change how the snapshot is generated. On machines with certain settings
-    # (like LANG=C or -Eascii-8bit) this could have been changed. So here we're
-    # going to force it to be UTF-8 to keep the snapshots consistent.
-    def setup
-      @previous_default_external = Encoding.default_external
-      ignore_warnings { Encoding.default_external = Encoding::UTF_8 }
-    end
-
-    def teardown
-      ignore_warnings { Encoding.default_external = @previous_default_external }
-    end
-
-    def test_empty_string
-      result = Prism.parse("")
-      assert_equal [], result.value.statements.body
-    end
-
-    def test_parse_takes_file_path
-      filepath = "filepath.rb"
-      result = Prism.parse("def foo; __FILE__; end", filepath: filepath)
-
-      assert_equal filepath, find_source_file_node(result.value).filepath
-    end
-
-    def test_parse_takes_line
-      line = 4
-      result = Prism.parse("def foo\n __FILE__\nend", line: line)
-
-      assert_equal line, result.value.location.start_line
-      assert_equal line + 1, find_source_file_node(result.value).location.start_line
-
-      result = Prism.parse_lex("def foo\n __FILE__\nend", line: line)
-      assert_equal line, result.value.first.location.start_line
-    end
-
-    def test_parse_takes_negative_lines
-      line = -2
-      result = Prism.parse("def foo\n __FILE__\nend", line: line)
-
-      assert_equal line, result.value.location.start_line
-      assert_equal line + 1, find_source_file_node(result.value).location.start_line
-
-      result = Prism.parse_lex("def foo\n __FILE__\nend", line: line)
-      assert_equal line, result.value.first.location.start_line
-    end
-
-    def test_parse_lex
-      node, tokens = Prism.parse_lex("def foo; end").value
-
-      assert_kind_of ProgramNode, node
-      assert_equal 5, tokens.length
-    end
-
-    if !ENV["PRISM_BUILD_MINIMAL"]
-      def test_dump_file
-        assert_nothing_raised do
-          Prism.dump_file(__FILE__)
-        end
-
-        error = assert_raise Errno::ENOENT do
-          Prism.dump_file("idontexist.rb")
-        end
-
-        assert_equal "No such file or directory - idontexist.rb", error.message
-
-        assert_raise TypeError do
-          Prism.dump_file(nil)
-        end
-      end
-    end
-
-    def test_lex_file
-      assert_nothing_raised do
-        Prism.lex_file(__FILE__)
-      end
-
-      error = assert_raise Errno::ENOENT do
-        Prism.lex_file("idontexist.rb")
-      end
-
-      assert_equal "No such file or directory - idontexist.rb", error.message
-
-      assert_raise TypeError do
-        Prism.lex_file(nil)
-      end
-    end
-
-    def test_parse_lex_file
-      node, tokens = Prism.parse_lex_file(__FILE__).value
-
-      assert_kind_of ProgramNode, node
-      refute_empty tokens
-
-      error = assert_raise Errno::ENOENT do
-        Prism.parse_lex_file("idontexist.rb")
-      end
-
-      assert_equal "No such file or directory - idontexist.rb", error.message
-
-      assert_raise TypeError do
-        Prism.parse_lex_file(nil)
-      end
-    end
-
-    def test_parse_file
-      node = Prism.parse_file(__FILE__).value
-      assert_kind_of ProgramNode, node
-
-      error = assert_raise Errno::ENOENT do
-        Prism.parse_file("idontexist.rb")
-      end
-
-      assert_equal "No such file or directory - idontexist.rb", error.message
-
-      assert_raise TypeError do
-        Prism.parse_file(nil)
-      end
-    end
-
-    def test_parse_file_success
-      assert_predicate Prism.parse_file_comments(__FILE__), :any?
-
-      error = assert_raise Errno::ENOENT do
-        Prism.parse_file_comments("idontexist.rb")
-      end
-
-      assert_equal "No such file or directory - idontexist.rb", error.message
-
-      assert_raise TypeError do
-        Prism.parse_file_comments(nil)
-      end
-    end
-
-    def test_parse_file_comments
-      assert_predicate Prism.parse_file_comments(__FILE__), :any?
-
-      error = assert_raise Errno::ENOENT do
-        Prism.parse_file_comments("idontexist.rb")
-      end
-
-      assert_equal "No such file or directory - idontexist.rb", error.message
-
-      assert_raise TypeError do
-        Prism.parse_file_comments(nil)
-      end
-    end
-
-    # To accurately compare against Ripper, we need to make sure that we're
-    # running on CRuby 3.2+.
-    ripper_enabled = RUBY_ENGINE == "ruby" && RUBY_VERSION >= "3.2.0"
-
-    # The FOCUS environment variable allows you to specify one particular fixture
-    # to test, instead of all of them.
-    base = File.join(__dir__, "fixtures")
-    relatives = ENV["FOCUS"] ? [ENV["FOCUS"]] : Dir["**/*.txt", base: base]
-
-    relatives.each do |relative|
-      # These fail on TruffleRuby due to a difference in Symbol#inspect: :测试 vs :"测试"
-      next if RUBY_ENGINE == "truffleruby" and %w[emoji_method_calls.txt seattlerb/bug202.txt seattlerb/magic_encoding_comment.txt].include?(relative)
-
-      filepath = File.join(base, relative)
-      snapshot = File.expand_path(File.join("snapshots", relative), __dir__)
-
-      directory = File.dirname(snapshot)
-      FileUtils.mkdir_p(directory) unless File.directory?(directory)
-
-      ripper_should_match = ripper_enabled
-      check_valid_syntax = RUBY_VERSION >= "3.2.0"
-
-      case relative
-      when "seattlerb/pct_w_heredoc_interp_nested.txt"
-        # This file has changed behavior in Ripper in Ruby 3.3, so we skip it if
-        # we're on an earlier version.
-        ripper_should_match = false if RUBY_VERSION < "3.3.0"
-      when "seattlerb/heredoc_nested.txt", "whitequark/dedenting_heredoc.txt"
-        # It seems like there are some oddities with nested heredocs and ripper.
-        # Waiting for feedback on https://bugs.ruby-lang.org/issues/19838.
-        ripper_should_match = false
-      when "spanning_heredoc.txt", "spanning_heredoc_newlines.txt"
-        # Ripper seems to have a bug that the regex portions before and after
-        # the heredoc are combined into a single token. See
-        # https://bugs.ruby-lang.org/issues/19838.
-        ripper_should_match = false
-      when "heredocs_leading_whitespace.txt"
-        # Ruby < 3.3.0 cannot parse heredocs where there are leading whitespace
-        # characters in the heredoc start.
-        # Example: <<~'   EOF' or <<-'  EOF'
-        # https://bugs.ruby-lang.org/issues/19539
-        if RUBY_VERSION < "3.3.0"
-          ripper_should_match = false
-          check_valid_syntax = false
-        end
-      end
-
-      define_method "test_filepath_#{relative}" do
-        # First, read the source from the filepath. Use binmode to avoid
-        # converting CRLF on Windows, and explicitly set the external encoding
-        # to UTF-8 to override the binmode default.
-        source = File.read(filepath, binmode: true, external_encoding: Encoding::UTF_8)
-
-        # Make sure that the given source is valid syntax, otherwise we have an
-        # invalid fixture.
-        assert_valid_syntax(source) if check_valid_syntax
-
-        # Next, assert that there were no errors during parsing.
-        result = Prism.parse(source, filepath: relative)
-        assert_empty result.errors
-
-        # Next, pretty print the source.
-        printed = PP.pp(result.value, +"", 79)
-
-        if File.exist?(snapshot)
-          saved = File.read(snapshot)
-
-          # If the snapshot file exists, but the printed value does not match the
-          # snapshot, then update the snapshot file.
-          if printed != saved
-            File.write(snapshot, printed)
-            warn("Updated snapshot at #{snapshot}.")
-          end
-
-          # If the snapshot file exists, then assert that the printed value
-          # matches the snapshot.
-          assert_equal(saved, printed)
-        else
-          # If the snapshot file does not yet exist, then write it out now.
-          File.write(snapshot, printed)
-          warn("Created snapshot at #{snapshot}.")
-        end
-
-        if !ENV["PRISM_BUILD_MINIMAL"]
-          # Next, assert that the value can be serialized and deserialized
-          # without changing the shape of the tree.
-          assert_equal_nodes(result.value, Prism.load(source, Prism.dump(source, filepath: relative)).value)
-        end
-
-        # Next, check that the location ranges of each node in the tree are a
-        # superset of their respective child nodes.
-        assert_non_overlapping_locations(result.value)
-
-        # Next, assert that the newlines are in the expected places.
-        expected_newlines = [0]
-        source.b.scan("\n") { expected_newlines << $~.offset(0)[0] + 1 }
-        assert_equal expected_newlines, Prism.parse(source).source.offsets
-
-        if ripper_should_match
-          # Finally, assert that we can lex the source and get the same tokens as
-          # Ripper.
-          lex_result = Prism.lex_compat(source)
-          assert_equal [], lex_result.errors
-          tokens = lex_result.value
-
-          begin
-            Prism.lex_ripper(source).zip(tokens).each do |(ripper, prism)|
-              assert_equal ripper, prism
-            end
-          rescue SyntaxError
-            raise ArgumentError, "Test file has invalid syntax #{filepath}"
-          end
-
-          # Next, check that we get the correct number of magic comments when
-          # lexing with ripper.
-          expected = MagicCommentRipper.new(source).tap(&:parse).magic_comments
-          actual = result.magic_comments
-
-          assert_equal expected.length, actual.length
-          expected.zip(actual).each do |(expected_key, expected_value), magic_comment|
-            assert_equal expected_key, magic_comment.key
-            assert_equal expected_value, magic_comment.value
-          end
-        end
-      end
-    end
-
-    Dir["*.txt", base: base].each do |relative|
-      next if relative == "newline_terminated.txt" || relative == "spanning_heredoc_newlines.txt"
-
-      # We test every snippet (separated by \n\n) in isolation
-      # to ensure the parser does not try to read bytes further than the end of each snippet
-      define_method "test_individual_snippets_#{relative}" do
-        filepath = File.join(base, relative)
-
-        # First, read the source from the filepath. Use binmode to avoid converting CRLF on Windows,
-        # and explicitly set the external encoding to UTF-8 to override the binmode default.
-        file_contents = File.read(filepath, binmode: true, external_encoding: Encoding::UTF_8)
-
-        file_contents.split(/(?<=\S)\n\n(?=\S)/).each do |snippet|
-          snippet = snippet.rstrip
-          result = Prism.parse(snippet, filepath: relative)
-          assert_empty result.errors
-
-          if !ENV["PRISM_BUILD_MINIMAL"]
-            assert_equal_nodes(result.value, Prism.load(snippet, Prism.dump(snippet, filepath: relative)).value)
-          end
-        end
-      end
-    end
-
-    private
-
-    # Check that the location ranges of each node in the tree are a superset of
-    # their respective child nodes.
-    def assert_non_overlapping_locations(node)
-      queue = [node]
-
-      while (current = queue.shift)
-        # We only want to compare parent/child location overlap in the case that
-        # we are not looking at a heredoc. That's because heredoc locations are
-        # special in that they only use the declaration of the heredoc.
-        compare = !(current.is_a?(StringNode) ||
-                    current.is_a?(XStringNode) ||
-                    current.is_a?(InterpolatedStringNode) ||
-                    current.is_a?(InterpolatedXStringNode)) ||
-        !current.opening&.start_with?("<<")
-
-        current.child_nodes.each do |child|
-          # child_nodes can return nil values, so we need to skip those.
-          next unless child
-
-          # Now that we know we have a child node, add that to the queue.
-          queue << child
-
-          if compare
-            assert_operator current.location.start_offset, :<=, child.location.start_offset
-            assert_operator current.location.end_offset, :>=, child.location.end_offset
-          end
-        end
-      end
-    end
-
-    def find_source_file_node(program)
-      queue = [program]
-      while (node = queue.shift)
-        return node if node.is_a?(SourceFileNode)
-        queue.concat(node.compact_child_nodes)
-      end
-    end
-
-    def ignore_warnings
-      previous_verbosity = $VERBOSE
-      $VERBOSE = nil
-      yield
-    ensure
-      $VERBOSE = previous_verbosity
-    end
-  end
-end

test/prism/parser_test.rb

@@ -1,186 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "test_helper"
-
-begin
-  verbose, $VERBOSE = $VERBOSE, nil
-  require "parser/ruby33"
-  require "prism/translation/parser33"
-rescue LoadError
-  # In CRuby's CI, we're not going to test against the parser gem because we
-  # don't want to have to install it. So in this case we'll just skip this test.
-  return
-ensure
-  $VERBOSE = verbose
-end
-
-# First, opt in to every AST feature.
-Parser::Builders::Default.modernize
-
-# Modify the source map == check so that it doesn't check against the node
-# itself so we don't get into a recursive loop.
-Parser::Source::Map.prepend(
-  Module.new {
-    def ==(other)
-      self.class == other.class &&
-        (instance_variables - %i[@node]).map do |ivar|
-          instance_variable_get(ivar) == other.instance_variable_get(ivar)
-        end.reduce(:&)
-    end
-  }
-)
-
-# Next, ensure that we're comparing the nodes and also comparing the source
-# ranges so that we're getting all of the necessary information.
-Parser::AST::Node.prepend(
-  Module.new {
-    def ==(other)
-      super && (location == other.location)
-    end
-  }
-)
-
-module Prism
-  class ParserTest < TestCase
-    base = File.join(__dir__, "fixtures")
-
-    # These files are erroring because of the parser gem being wrong.
-    skip_incorrect = [
-      "embdoc_no_newline_at_end.txt"
-    ]
-
-    # These files are either failing to parse or failing to translate, so we'll
-    # skip them for now.
-    skip_all = skip_incorrect | [
-      "dash_heredocs.txt",
-      "dos_endings.txt",
-      "heredocs_with_ignored_newlines.txt",
-      "regex.txt",
-      "regex_char_width.txt",
-      "spanning_heredoc.txt",
-      "spanning_heredoc_newlines.txt",
-      "unescaping.txt"
-    ]
-
-    # Not sure why these files are failing on JRuby, but skipping them for now.
-    if RUBY_ENGINE == "jruby"
-      skip_all.push("emoji_method_calls.txt", "symbols.txt")
-    end
-
-    # These files are failing to translate their lexer output into the lexer
-    # output expected by the parser gem, so we'll skip them for now.
-    skip_tokens = [
-      "comments.txt",
-      "heredoc_with_comment.txt",
-      "indented_file_end.txt",
-      "methods.txt",
-      "strings.txt",
-      "tilde_heredocs.txt",
-      "xstring_with_backslash.txt"
-    ]
-
-    Dir["*.txt", base: base].each do |name|
-      next if skip_all.include?(name)
-
-      define_method("test_#{name}") do
-        assert_equal_parses(File.join(base, name), compare_tokens: !skip_tokens.include?(name))
-      end
-    end
-
-    private
-
-    def assert_equal_parses(filepath, compare_tokens: true)
-      buffer = Parser::Source::Buffer.new(filepath, 1)
-      buffer.source = File.read(filepath)
-
-      parser = Parser::Ruby33.new
-      parser.diagnostics.consumer = ->(*) {}
-      parser.diagnostics.all_errors_are_fatal = true
-
-      expected_ast, expected_comments, expected_tokens =
-        begin
-          parser.tokenize(buffer)
-        rescue ArgumentError, Parser::SyntaxError
-          return
-        end
-
-      actual_ast, actual_comments, actual_tokens =
-        Prism::Translation::Parser33.new.tokenize(buffer)
-
-      assert_equal expected_ast, actual_ast, -> { assert_equal_asts_message(expected_ast, actual_ast) }
-      assert_equal_tokens(expected_tokens, actual_tokens) if compare_tokens
-      assert_equal_comments(expected_comments, actual_comments)
-    end
-
-    def assert_equal_asts_message(expected_ast, actual_ast)
-      queue = [[expected_ast, actual_ast]]
-
-      while (left, right = queue.shift)
-        if left.type != right.type
-          return "expected: #{left.type}\nactual: #{right.type}"
-        end
-
-        if left.location != right.location
-          return "expected:\n#{left.inspect}\n#{left.location.inspect}\nactual:\n#{right.inspect}\n#{right.location.inspect}"
-        end
-
-        if left.type == :str && left.children[0] != right.children[0]
-          return "expected: #{left.inspect}\nactual: #{right.inspect}"
-        end
-
-        left.children.zip(right.children).each do |left_child, right_child|
-          queue << [left_child, right_child] if left_child.is_a?(Parser::AST::Node)
-        end
-      end
-
-      "expected: #{expected_ast.inspect}\nactual: #{actual_ast.inspect}"
-    end
-
-    def assert_equal_tokens(expected_tokens, actual_tokens)
-      if expected_tokens != actual_tokens
-        expected_index = 0
-        actual_index = 0
-
-        while expected_index < expected_tokens.length
-          expected_token = expected_tokens[expected_index]
-          actual_token = actual_tokens[actual_index]
-
-          expected_index += 1
-          actual_index += 1
-
-          # The parser gem always has a space before a string end in list
-          # literals, but we don't. So we'll skip over the space.
-          if expected_token[0] == :tSPACE && actual_token[0] == :tSTRING_END
-            expected_index += 1
-            next
-          end
-
-          # There are a lot of tokens that have very specific meaning according
-          # to the context of the parser. We don't expose that information in
-          # prism, so we need to normalize these tokens a bit.
-          case actual_token[0]
-          when :kDO
-            actual_token[0] = expected_token[0] if %i[kDO_BLOCK kDO_LAMBDA].include?(expected_token[0])
-          when :tLPAREN
-            actual_token[0] = expected_token[0] if expected_token[0] == :tLPAREN2
-          when :tPOW
-            actual_token[0] = expected_token[0] if expected_token[0] == :tDSTAR
-          end
-
-          # Now we can assert that the tokens are actually equal.
-          assert_equal expected_token, actual_token, -> {
-            "expected: #{expected_token.inspect}\n" \
-            "actual: #{actual_token.inspect}"
-          }
-        end
-      end
-    end
-
-    def assert_equal_comments(expected_comments, actual_comments)
-      assert_equal expected_comments, actual_comments, -> {
-        "expected: #{expected_comments.inspect}\n" \
-        "actual: #{actual_comments.inspect}"
-      }
-    end
-  end
-end

test/prism/regexp_test.rb

@@ -223,12 +223,12 @@ module Prism
 
     def test_last_encoding_option_wins
       regex = "/foo/nu"
-      option = Prism.parse(regex).value.statements.body.first.options
+      option = Prism.parse_statement(regex).options
 
       assert_equal Regexp::FIXEDENCODING, option
 
       regex = "/foo/un"
-      option = Prism.parse(regex).value.statements.body.first.options
+      option = Prism.parse_statement(regex).options
 
       assert_equal Regexp::NOENCODING, option
     end
@@ -246,7 +246,7 @@ module Prism
     def options(flags)
       options =
         ["/foo/#{flags}", "/foo\#{1}/#{flags}"].map do |source|
-          Prism.parse(source).value.statements.body.first.options
+          Prism.parse_statement(source).options
         end
 
       # Check that we get the same set of options from both regular expressions

test/prism/result/attribute_write_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class AttributeWriteTest < TestCase
@@ -41,18 +41,14 @@ module Prism
 
     private
 
-    def parse(source)
-      Prism.parse(source).value.statements.body.first
-    end
-
     def assert_attribute_write(source)
-      call = parse(source)
+      call = Prism.parse_statement(source)
       assert(call.attribute_write?)
       assert_equal(1, eval(source))
     end
 
     def refute_attribute_write(source)
-      call = parse(source)
+      call = Prism.parse_statement(source)
       refute(call.attribute_write?)
       refute_equal(1, eval(source))
     end

test/prism/result/comments_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class CommentsTest < TestCase

test/prism/result/constant_path_node_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class ConstantPathNodeTest < TestCase
@@ -11,7 +11,7 @@ module Prism
             Qux
       RUBY
 
-      constant_path = Prism.parse(source).value.statements.body.first
+      constant_path = Prism.parse_statement(source)
       assert_equal("Foo::Bar::Baz::Qux", constant_path.full_name)
     end
 
@@ -22,7 +22,7 @@ module Prism
             Qux
       RUBY
 
-      constant_path = Prism.parse(source).value.statements.body.first
+      constant_path = Prism.parse_statement(source)
       assert_raise(ConstantPathNode::DynamicPartsInConstantPathError) do
         constant_path.full_name
       end
@@ -35,7 +35,7 @@ module Prism
             Qux
       RUBY
 
-      constant_path = Prism.parse(source).value.statements.body.first
+      constant_path = Prism.parse_statement(source)
 
       assert_raise(ConstantPathNode::DynamicPartsInConstantPathError) do
         constant_path.full_name
@@ -49,7 +49,7 @@ module Prism
             Qux, Something = [1, 2]
       RUBY
 
-      node = Prism.parse(source).value.statements.body.first
+      node = Prism.parse_statement(source)
       assert_equal("Foo::Bar::Baz::Qux", node.lefts.first.full_name)
     end
 
@@ -60,7 +60,7 @@ module Prism
             Qux, Something = [1, 2]
       RUBY
 
-      node = Prism.parse(source).value.statements.body.first
+      node = Prism.parse_statement(source)
       assert_equal("::Foo::Bar::Baz::Qux", node.lefts.first.full_name)
     end
 
@@ -69,7 +69,7 @@ module Prism
         self::Foo, Bar = [1, 2]
       RUBY
 
-      constant_target = Prism.parse(source).value.statements.body.first
+      constant_target = Prism.parse_statement(source)
       dynamic, static = constant_target.lefts
 
       assert_raise(ConstantPathNode::DynamicPartsInConstantPathError) do
@@ -84,7 +84,7 @@ module Prism
         Bar
       RUBY
 
-      constant = Prism.parse(source).value.statements.body.first
+      constant = Prism.parse_statement(source)
       assert_equal("Bar", constant.full_name)
     end
   end

test/prism/result/equality_test.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class EqualityTest < TestCase
+    def test_equality
+      assert_operator Prism.parse_statement("1"), :===, Prism.parse_statement("1")
+      assert_operator Prism.parse("1").value, :===, Prism.parse("1").value
+
+      complex_source = "class Something; @var = something.else { _1 }; end"
+      assert_operator Prism.parse_statement(complex_source), :===, Prism.parse_statement(complex_source)
+
+      refute_operator Prism.parse_statement("1"), :===, Prism.parse_statement("2")
+      refute_operator Prism.parse_statement("1"), :===, Prism.parse_statement("0x1")
+
+      complex_source_1 = "class Something; @var = something.else { _1 }; end"
+      complex_source_2 = "class Something; @var = something.else { _2 }; end"
+      refute_operator Prism.parse_statement(complex_source_1), :===, Prism.parse_statement(complex_source_2)
+    end
+  end
+end

test/prism/result/heredoc_test.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class HeredocTest < TestCase
+    def test_heredoc?
+      refute Prism.parse_statement("\"foo\"").heredoc?
+      refute Prism.parse_statement("\"foo \#{1}\"").heredoc?
+      refute Prism.parse_statement("`foo`").heredoc?
+      refute Prism.parse_statement("`foo \#{1}`").heredoc?
+
+      assert Prism.parse_statement("<<~HERE\nfoo\nHERE\n").heredoc?
+      assert Prism.parse_statement("<<~HERE\nfoo \#{1}\nHERE\n").heredoc?
+      assert Prism.parse_statement("<<~`HERE`\nfoo\nHERE\n").heredoc?
+      assert Prism.parse_statement("<<~`HERE`\nfoo \#{1}\nHERE\n").heredoc?
+    end
+  end
+end

test/prism/result/index_write_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class IndexWriteTest < TestCase

test/prism/result/integer_base_flags_test.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class IntegerBaseFlagsTest < TestCase
+    # Through some bit hackery, we want to allow consumers to use the integer
+    # base flags as the base itself. It has a nice property that the current
+    # alignment provides them in the correct order. So here we test that our
+    # assumption holds so that it doesn't change out from under us.
+    #
+    # In C, this would look something like:
+    #
+    #     ((flags & ~DECIMAL) << 1) || 10
+    #
+    # We have to do some other work in Ruby because 0 is truthy and ~ on an
+    # integer doesn't have a fixed width.
+    def test_flags
+      assert_equal 2, base("0b1")
+      assert_equal 8, base("0o1")
+      assert_equal 10, base("0d1")
+      assert_equal 16, base("0x1")
+    end
+
+    private
+
+    def base(source)
+      node = Prism.parse_statement(source)
+      value = (node.send(:flags) & (0b1111 - IntegerBaseFlags::DECIMAL)) << 1
+      value == 0 ? 10 : value
+    end
+  end
+end

test/prism/result/integer_parse_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class IntegerParseTest < TestCase
@@ -35,7 +35,7 @@ module Prism
     private
 
     def assert_integer_parse(expected, source = expected.to_s)
-      assert_equal expected, Prism.parse(source).value.statements.body.first.value
+      assert_equal expected, Prism.parse_statement(source).value
     end
   end
 end

test/prism/result/numeric_value_test.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class NumericValueTest < TestCase
+    def test_numeric_value
+      assert_equal 123, Prism.parse_statement("123").value
+      assert_equal 3.14, Prism.parse_statement("3.14").value
+      assert_equal 42i, Prism.parse_statement("42i").value
+      assert_equal 42.1ri, Prism.parse_statement("42.1ri").value
+      assert_equal 3.14i, Prism.parse_statement("3.14i").value
+      assert_equal 42r, Prism.parse_statement("42r").value
+      assert_equal 0.5r, Prism.parse_statement("0.5r").value
+      assert_equal 42ri, Prism.parse_statement("42ri").value
+      assert_equal 0.5ri, Prism.parse_statement("0.5ri").value
+      assert_equal 0xFFr, Prism.parse_statement("0xFFr").value
+      assert_equal 0xFFri, Prism.parse_statement("0xFFri").value
+    end
+  end
+end

test/prism/result/overlap_test.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class OverlapTest < TestCase
+    Fixture.each do |fixture|
+      define_method(fixture.test_name) { assert_overlap(fixture) }
+    end
+
+    private
+
+    # Check that the location ranges of each node in the tree are a superset of
+    # their respective child nodes.
+    def assert_overlap(fixture)
+      queue = [Prism.parse_file(fixture.full_path).value]
+
+      while (current = queue.shift)
+        # We only want to compare parent/child location overlap in the case that
+        # we are not looking at a heredoc. That's because heredoc locations are
+        # special in that they only use the declaration of the heredoc.
+        compare = !(current.is_a?(StringNode) ||
+                    current.is_a?(XStringNode) ||
+                    current.is_a?(InterpolatedStringNode) ||
+                    current.is_a?(InterpolatedXStringNode)) ||
+        !current.opening&.start_with?("<<")
+
+        current.child_nodes.each do |child|
+          # child_nodes can return nil values, so we need to skip those.
+          next unless child
+
+          # Now that we know we have a child node, add that to the queue.
+          queue << child
+
+          if compare
+            assert_operator current.location.start_offset, :<=, child.location.start_offset
+            assert_operator current.location.end_offset, :>=, child.location.end_offset
+          end
+        end
+      end
+    end
+  end
+end

test/prism/result/redundant_return_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class RedundantReturnTest < TestCase

test/prism/result/regular_expression_options_test.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class RegularExpressionOptionsTest < TestCase
+    def test_options
+      assert_equal "", Prism.parse_statement("__FILE__").filepath
+      assert_equal "foo.rb", Prism.parse_statement("__FILE__", filepath: "foo.rb").filepath
+
+      assert_equal 1, Prism.parse_statement("foo").location.start_line
+      assert_equal 10, Prism.parse_statement("foo", line: 10).location.start_line
+
+      refute Prism.parse_statement("\"foo\"").frozen?
+      assert Prism.parse_statement("\"foo\"", frozen_string_literal: true).frozen?
+      refute Prism.parse_statement("\"foo\"", frozen_string_literal: false).frozen?
+
+      assert_kind_of CallNode, Prism.parse_statement("foo")
+      assert_kind_of LocalVariableReadNode, Prism.parse_statement("foo", scopes: [[:foo]])
+      assert_equal 1, Prism.parse_statement("foo", scopes: [[:foo], []]).depth
+
+      assert_equal [:foo], Prism.parse("foo", scopes: [[:foo]]).value.locals
+    end
+  end
+end

test/prism/result/source_location_test.rb

@@ -1,9 +1,9 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
-  class LocationTest < TestCase
+  class SourceLocationTest < TestCase
     def test_AliasGlobalVariableNode
       assert_location(AliasGlobalVariableNode, "alias $foo $bar")
     end
@@ -921,7 +921,7 @@ module Prism
 
     def test_all_tested
       expected = Prism.constants.grep(/.Node$/).sort - %i[MissingNode ProgramNode]
-      actual = LocationTest.instance_methods(false).grep(/.Node$/).map { |name| name[5..].to_sym }.sort
+      actual = SourceLocationTest.instance_methods(false).grep(/.Node$/).map { |name| name[5..].to_sym }.sort
       assert_equal expected, actual
     end
 

test/prism/result/static_inspect_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class StaticInspectTest < TestCase

test/prism/result/static_literals_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class StaticLiteralsTest < TestCase

test/prism/result/warnings_test.rb

@@ -2,8 +2,7 @@
 
 return if RUBY_VERSION < "3.1"
 
-require_relative "test_helper"
-require "stringio"
+require_relative "../test_helper"
 
 module Prism
   class WarningsTest < TestCase

test/prism/ruby/compiler_test.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 # typed: ignore
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class CompilerTest < TestCase

test/prism/ruby/desugar_compiler_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class DesugarCompilerTest < TestCase

test/prism/ruby/dispatcher_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class DispatcherTest < TestCase

test/prism/ruby/location_test.rb

@@ -0,0 +1,173 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class LocationTest < TestCase
+    def test_join
+      call = Prism.parse_statement("1234 + 567")
+      receiver = call.receiver
+      argument = call.arguments.arguments.first
+
+      joined = receiver.location.join(argument.location)
+      assert_equal 0, joined.start_offset
+      assert_equal 10, joined.length
+
+      assert_raise(RuntimeError, "Incompatible locations") do
+        argument.location.join(receiver.location)
+      end
+
+      other_argument = Prism.parse_statement("1234 + 567").arguments.arguments.first
+
+      assert_raise(RuntimeError, "Incompatible sources") do
+        other_argument.location.join(receiver.location)
+      end
+
+      assert_raise(RuntimeError, "Incompatible sources") do
+        receiver.location.join(other_argument.location)
+      end
+    end
+
+    def test_character_offsets
+      program = Prism.parse("😀 + 😀\n😍 ||= 😍").value
+
+      # first 😀
+      location = program.statements.body.first.receiver.location
+      assert_equal 0, location.start_character_offset
+      assert_equal 1, location.end_character_offset
+      assert_equal 0, location.start_character_column
+      assert_equal 1, location.end_character_column
+
+      # second 😀
+      location = program.statements.body.first.arguments.arguments.first.location
+      assert_equal 4, location.start_character_offset
+      assert_equal 5, location.end_character_offset
+      assert_equal 4, location.start_character_column
+      assert_equal 5, location.end_character_column
+
+      # first 😍
+      location = program.statements.body.last.name_loc
+      assert_equal 6, location.start_character_offset
+      assert_equal 7, location.end_character_offset
+      assert_equal 0, location.start_character_column
+      assert_equal 1, location.end_character_column
+
+      # second 😍
+      location = program.statements.body.last.value.location
+      assert_equal 12, location.start_character_offset
+      assert_equal 13, location.end_character_offset
+      assert_equal 6, location.start_character_column
+      assert_equal 7, location.end_character_column
+    end
+
+    def test_code_units
+      program = Prism.parse("😀 + 😀\n😍 ||= 😍").value
+
+      # first 😀
+      location = program.statements.body.first.receiver.location
+
+      assert_equal 0, location.start_code_units_offset(Encoding::UTF_8)
+      assert_equal 0, location.start_code_units_offset(Encoding::UTF_16LE)
+      assert_equal 0, location.start_code_units_offset(Encoding::UTF_32LE)
+
+      assert_equal 1, location.end_code_units_offset(Encoding::UTF_8)
+      assert_equal 2, location.end_code_units_offset(Encoding::UTF_16LE)
+      assert_equal 1, location.end_code_units_offset(Encoding::UTF_32LE)
+
+      assert_equal 0, location.start_code_units_column(Encoding::UTF_8)
+      assert_equal 0, location.start_code_units_column(Encoding::UTF_16LE)
+      assert_equal 0, location.start_code_units_column(Encoding::UTF_32LE)
+
+      assert_equal 1, location.end_code_units_column(Encoding::UTF_8)
+      assert_equal 2, location.end_code_units_column(Encoding::UTF_16LE)
+      assert_equal 1, location.end_code_units_column(Encoding::UTF_32LE)
+
+      # second 😀
+      location = program.statements.body.first.arguments.arguments.first.location
+
+      assert_equal 4, location.start_code_units_offset(Encoding::UTF_8)
+      assert_equal 5, location.start_code_units_offset(Encoding::UTF_16LE)
+      assert_equal 4, location.start_code_units_offset(Encoding::UTF_32LE)
+
+      assert_equal 5, location.end_code_units_offset(Encoding::UTF_8)
+      assert_equal 7, location.end_code_units_offset(Encoding::UTF_16LE)
+      assert_equal 5, location.end_code_units_offset(Encoding::UTF_32LE)
+
+      assert_equal 4, location.start_code_units_column(Encoding::UTF_8)
+      assert_equal 5, location.start_code_units_column(Encoding::UTF_16LE)
+      assert_equal 4, location.start_code_units_column(Encoding::UTF_32LE)
+
+      assert_equal 5, location.end_code_units_column(Encoding::UTF_8)
+      assert_equal 7, location.end_code_units_column(Encoding::UTF_16LE)
+      assert_equal 5, location.end_code_units_column(Encoding::UTF_32LE)
+
+      # first 😍
+      location = program.statements.body.last.name_loc
+
+      assert_equal 6, location.start_code_units_offset(Encoding::UTF_8)
+      assert_equal 8, location.start_code_units_offset(Encoding::UTF_16LE)
+      assert_equal 6, location.start_code_units_offset(Encoding::UTF_32LE)
+
+      assert_equal 7, location.end_code_units_offset(Encoding::UTF_8)
+      assert_equal 10, location.end_code_units_offset(Encoding::UTF_16LE)
+      assert_equal 7, location.end_code_units_offset(Encoding::UTF_32LE)
+
+      assert_equal 0, location.start_code_units_column(Encoding::UTF_8)
+      assert_equal 0, location.start_code_units_column(Encoding::UTF_16LE)
+      assert_equal 0, location.start_code_units_column(Encoding::UTF_32LE)
+
+      assert_equal 1, location.end_code_units_column(Encoding::UTF_8)
+      assert_equal 2, location.end_code_units_column(Encoding::UTF_16LE)
+      assert_equal 1, location.end_code_units_column(Encoding::UTF_32LE)
+
+      # second 😍
+      location = program.statements.body.last.value.location
+
+      assert_equal 12, location.start_code_units_offset(Encoding::UTF_8)
+      assert_equal 15, location.start_code_units_offset(Encoding::UTF_16LE)
+      assert_equal 12, location.start_code_units_offset(Encoding::UTF_32LE)
+
+      assert_equal 13, location.end_code_units_offset(Encoding::UTF_8)
+      assert_equal 17, location.end_code_units_offset(Encoding::UTF_16LE)
+      assert_equal 13, location.end_code_units_offset(Encoding::UTF_32LE)
+
+      assert_equal 6, location.start_code_units_column(Encoding::UTF_8)
+      assert_equal 7, location.start_code_units_column(Encoding::UTF_16LE)
+      assert_equal 6, location.start_code_units_column(Encoding::UTF_32LE)
+
+      assert_equal 7, location.end_code_units_column(Encoding::UTF_8)
+      assert_equal 9, location.end_code_units_column(Encoding::UTF_16LE)
+      assert_equal 7, location.end_code_units_column(Encoding::UTF_32LE)
+    end
+
+    def test_chop
+      location = Prism.parse("foo").value.location
+
+      assert_equal "fo", location.chop.slice
+      assert_equal "", location.chop.chop.chop.slice
+
+      # Check that we don't go negative.
+      10.times { location = location.chop }
+      assert_equal "", location.slice
+    end
+
+    def test_slice_lines
+      method = Prism.parse_statement("\nprivate def foo\nend\n").arguments.arguments.first
+
+      assert_equal "private def foo\nend\n", method.slice_lines
+    end
+
+    def test_adjoin
+      program = Prism.parse("foo.bar = 1").value
+
+      location = program.statements.body.first.message_loc
+      adjoined = location.adjoin("=")
+
+      assert_kind_of Location, adjoined
+      refute_equal location, adjoined
+
+      assert_equal 4, adjoined.start_offset
+      assert_equal 9, adjoined.end_offset
+    end
+  end
+end

test/prism/ruby/parameters_signature_test.rb

@@ -1,9 +1,9 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
-
 return if RUBY_VERSION < "3.2"
 
+require_relative "../test_helper"
+
 module Prism
   class ParametersSignatureTest < TestCase
     def test_req
@@ -56,7 +56,6 @@ module Prism
 
     def test_key_ordering
       omit("TruffleRuby returns keys in order they were declared") if RUBY_ENGINE == "truffleruby"
-
       assert_parameters([[:keyreq, :a], [:keyreq, :b], [:key, :c], [:key, :d]], "a:, c: 1, b:, d: 2")
     end
 
@@ -75,14 +74,13 @@ module Prism
     private
 
     def assert_parameters(expected, source)
-      eval("def self.m(#{source}); end")
-
-      begin
-        assert_equal(expected, method(:m).parameters)
+      # Compare against our expectation.
       assert_equal(expected, signature(source))
-      ensure
-        singleton_class.undef_method(:m)
-      end
+
+      # Compare against Ruby's expectation.
+      object = Object.new
+      eval("def object.m(#{source}); end")
+      assert_equal(expected, object.method(:m).parameters)
     end
 
     def signature(source)

test/prism/ruby/parser_test.rb

@@ -0,0 +1,288 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+begin
+  verbose, $VERBOSE = $VERBOSE, nil
+  require "parser/ruby33"
+  require "prism/translation/parser33"
+rescue LoadError
+  # In CRuby's CI, we're not going to test against the parser gem because we
+  # don't want to have to install it. So in this case we'll just skip this test.
+  return
+ensure
+  $VERBOSE = verbose
+end
+
+# First, opt in to every AST feature.
+Parser::Builders::Default.modernize
+
+# Modify the source map == check so that it doesn't check against the node
+# itself so we don't get into a recursive loop.
+Parser::Source::Map.prepend(
+  Module.new {
+    def ==(other)
+      self.class == other.class &&
+        (instance_variables - %i[@node]).map do |ivar|
+          instance_variable_get(ivar) == other.instance_variable_get(ivar)
+        end.reduce(:&)
+    end
+  }
+)
+
+# Next, ensure that we're comparing the nodes and also comparing the source
+# ranges so that we're getting all of the necessary information.
+Parser::AST::Node.prepend(
+  Module.new {
+    def ==(other)
+      super && (location == other.location)
+    end
+  }
+)
+
+module Prism
+  class ParserTest < TestCase
+    # These files are erroring because of the parser gem being wrong.
+    skip_incorrect = [
+      "embdoc_no_newline_at_end.txt"
+    ]
+
+    # These files are either failing to parse or failing to translate, so we'll
+    # skip them for now.
+    skip_all = skip_incorrect | [
+      "dash_heredocs.txt",
+      "dos_endings.txt",
+      "heredocs_with_ignored_newlines.txt",
+      "regex.txt",
+      "regex_char_width.txt",
+      "spanning_heredoc.txt",
+      "spanning_heredoc_newlines.txt",
+      "unescaping.txt",
+      "seattlerb/backticks_interpolation_line.txt",
+      "seattlerb/block_decomp_anon_splat_arg.txt",
+      "seattlerb/block_decomp_arg_splat_arg.txt",
+      "seattlerb/block_decomp_arg_splat.txt",
+      "seattlerb/block_decomp_splat.txt",
+      "seattlerb/block_paren_splat.txt",
+      "seattlerb/bug190.txt",
+      "seattlerb/case_in_hash_pat_rest_solo.txt",
+      "seattlerb/case_in_hash_pat_rest.txt",
+      "seattlerb/case_in.txt",
+      "seattlerb/heredoc_nested.txt",
+      "seattlerb/heredoc_squiggly_blank_line_plus_interpolation.txt",
+      "seattlerb/heredoc_with_carriage_return_escapes_windows.txt",
+      "seattlerb/heredoc_with_carriage_return_escapes.txt",
+      "seattlerb/heredoc_with_extra_carriage_returns_windows.txt",
+      "seattlerb/heredoc_with_only_carriage_returns_windows.txt",
+      "seattlerb/heredoc_with_only_carriage_returns.txt",
+      "seattlerb/masgn_double_paren.txt",
+      "seattlerb/parse_line_heredoc_hardnewline.txt",
+      "seattlerb/parse_pattern_044.txt",
+      "seattlerb/parse_pattern_058_2.txt",
+      "seattlerb/parse_pattern_058.txt",
+      "seattlerb/pct_nl.txt",
+      "seattlerb/pctW_lineno.txt",
+      "seattlerb/regexp_esc_C_slash.txt",
+      "seattlerb/TestRubyParserShared.txt",
+      "unparser/corpus/literal/assignment.txt",
+      "unparser/corpus/literal/block.txt",
+      "unparser/corpus/literal/def.txt",
+      "unparser/corpus/literal/dstr.txt",
+      "unparser/corpus/literal/literal.txt",
+      "unparser/corpus/literal/pattern.txt",
+      "unparser/corpus/semantic/dstr.txt",
+      "unparser/corpus/semantic/opasgn.txt",
+      "whitequark/dedenting_interpolating_heredoc_fake_line_continuation.txt",
+      "whitequark/masgn_nested.txt",
+      "whitequark/newline_in_hash_argument.txt",
+      "whitequark/parser_bug_640.txt",
+      "whitequark/parser_slash_slash_n_escaping_in_literals.txt",
+      "whitequark/ruby_bug_11989.txt",
+      "whitequark/slash_newline_in_heredocs.txt",
+      "whitequark/unary_num_pow_precedence.txt"
+    ]
+
+    # Not sure why these files are failing on JRuby, but skipping them for now.
+    if RUBY_ENGINE == "jruby"
+      skip_all.push("emoji_method_calls.txt", "symbols.txt")
+    end
+
+    # These files are failing to translate their lexer output into the lexer
+    # output expected by the parser gem, so we'll skip them for now.
+    skip_tokens = [
+      "comments.txt",
+      "heredoc_with_comment.txt",
+      "indented_file_end.txt",
+      "methods.txt",
+      "strings.txt",
+      "tilde_heredocs.txt",
+      "xstring_with_backslash.txt",
+      "seattlerb/bug169.txt",
+      "seattlerb/class_comments.txt",
+      "seattlerb/difficult4__leading_dots2.txt",
+      "seattlerb/difficult6__7.txt",
+      "seattlerb/difficult6__8.txt",
+      "seattlerb/dsym_esc_to_sym.txt",
+      "seattlerb/heredoc__backslash_dos_format.txt",
+      "seattlerb/heredoc_backslash_nl.txt",
+      "seattlerb/heredoc_comma_arg.txt",
+      "seattlerb/heredoc_squiggly_blank_lines.txt",
+      "seattlerb/heredoc_squiggly_interp.txt",
+      "seattlerb/heredoc_squiggly_tabs_extra.txt",
+      "seattlerb/heredoc_squiggly_tabs.txt",
+      "seattlerb/heredoc_squiggly_visually_blank_lines.txt",
+      "seattlerb/heredoc_squiggly.txt",
+      "seattlerb/heredoc_unicode.txt",
+      "seattlerb/heredoc_with_interpolation_and_carriage_return_escapes_windows.txt",
+      "seattlerb/heredoc_with_interpolation_and_carriage_return_escapes.txt",
+      "seattlerb/interpolated_symbol_array_line_breaks.txt",
+      "seattlerb/interpolated_word_array_line_breaks.txt",
+      "seattlerb/label_vs_string.txt",
+      "seattlerb/module_comments.txt",
+      "seattlerb/non_interpolated_symbol_array_line_breaks.txt",
+      "seattlerb/non_interpolated_word_array_line_breaks.txt",
+      "seattlerb/parse_line_block_inline_comment_leading_newlines.txt",
+      "seattlerb/parse_line_block_inline_comment.txt",
+      "seattlerb/parse_line_block_inline_multiline_comment.txt",
+      "seattlerb/parse_line_dstr_escaped_newline.txt",
+      "seattlerb/parse_line_heredoc.txt",
+      "seattlerb/parse_line_multiline_str_literal_n.txt",
+      "seattlerb/parse_line_str_with_newline_escape.txt",
+      "seattlerb/pct_Q_backslash_nl.txt",
+      "seattlerb/pct_w_heredoc_interp_nested.txt",
+      "seattlerb/qsymbols_empty_space.txt",
+      "seattlerb/qw_escape_term.txt",
+      "seattlerb/qWords_space.txt",
+      "seattlerb/read_escape_unicode_curlies.txt",
+      "seattlerb/read_escape_unicode_h4.txt",
+      "seattlerb/required_kwarg_no_value.txt",
+      "seattlerb/slashy_newlines_within_string.txt",
+      "seattlerb/str_double_escaped_newline.txt",
+      "seattlerb/str_double_newline.txt",
+      "seattlerb/str_evstr_escape.txt",
+      "seattlerb/str_newline_hash_line_number.txt",
+      "seattlerb/str_single_newline.txt",
+      "seattlerb/symbol_empty.txt",
+      "seattlerb/symbols_empty_space.txt",
+      "whitequark/args.txt",
+      "whitequark/beginless_erange_after_newline.txt",
+      "whitequark/beginless_irange_after_newline.txt",
+      "whitequark/bug_ascii_8bit_in_literal.txt",
+      "whitequark/bug_def_no_paren_eql_begin.txt",
+      "whitequark/dedenting_heredoc.txt",
+      "whitequark/dedenting_non_interpolating_heredoc_line_continuation.txt",
+      "whitequark/forward_arg_with_open_args.txt",
+      "whitequark/interp_digit_var.txt",
+      "whitequark/lbrace_arg_after_command_args.txt",
+      "whitequark/multiple_pattern_matches.txt",
+      "whitequark/parser_drops_truncated_parts_of_squiggly_heredoc.txt",
+      "whitequark/ruby_bug_11990.txt",
+      "whitequark/ruby_bug_14690.txt",
+      "whitequark/ruby_bug_9669.txt",
+      "whitequark/space_args_arg_block.txt",
+      "whitequark/space_args_block.txt"
+    ]
+
+    Fixture.each(except: skip_all) do |fixture|
+      define_method(fixture.test_name) do
+        assert_equal_parses(fixture, compare_tokens: !skip_tokens.include?(fixture.path))
+      end
+    end
+
+    private
+
+    def assert_equal_parses(fixture, compare_tokens: true)
+      buffer = Parser::Source::Buffer.new(fixture.path, 1)
+      buffer.source = fixture.read
+
+      parser = Parser::Ruby33.new
+      parser.diagnostics.consumer = ->(*) {}
+      parser.diagnostics.all_errors_are_fatal = true
+
+      expected_ast, expected_comments, expected_tokens =
+        begin
+          ignore_warnings { parser.tokenize(buffer) }
+        rescue ArgumentError, Parser::SyntaxError
+          return
+        end
+
+      actual_ast, actual_comments, actual_tokens =
+        ignore_warnings { Prism::Translation::Parser33.new.tokenize(buffer) }
+
+      assert_equal expected_ast, actual_ast, -> { assert_equal_asts_message(expected_ast, actual_ast) }
+      assert_equal_tokens(expected_tokens, actual_tokens) if compare_tokens
+      assert_equal_comments(expected_comments, actual_comments)
+    end
+
+    def assert_equal_asts_message(expected_ast, actual_ast)
+      queue = [[expected_ast, actual_ast]]
+
+      while (left, right = queue.shift)
+        if left.type != right.type
+          return "expected: #{left.type}\nactual: #{right.type}"
+        end
+
+        if left.location != right.location
+          return "expected:\n#{left.inspect}\n#{left.location.inspect}\nactual:\n#{right.inspect}\n#{right.location.inspect}"
+        end
+
+        if left.type == :str && left.children[0] != right.children[0]
+          return "expected: #{left.inspect}\nactual: #{right.inspect}"
+        end
+
+        left.children.zip(right.children).each do |left_child, right_child|
+          queue << [left_child, right_child] if left_child.is_a?(Parser::AST::Node)
+        end
+      end
+
+      "expected: #{expected_ast.inspect}\nactual: #{actual_ast.inspect}"
+    end
+
+    def assert_equal_tokens(expected_tokens, actual_tokens)
+      if expected_tokens != actual_tokens
+        expected_index = 0
+        actual_index = 0
+
+        while expected_index < expected_tokens.length
+          expected_token = expected_tokens[expected_index]
+          actual_token = actual_tokens[actual_index]
+
+          expected_index += 1
+          actual_index += 1
+
+          # The parser gem always has a space before a string end in list
+          # literals, but we don't. So we'll skip over the space.
+          if expected_token[0] == :tSPACE && actual_token[0] == :tSTRING_END
+            expected_index += 1
+            next
+          end
+
+          # There are a lot of tokens that have very specific meaning according
+          # to the context of the parser. We don't expose that information in
+          # prism, so we need to normalize these tokens a bit.
+          case actual_token[0]
+          when :kDO
+            actual_token[0] = expected_token[0] if %i[kDO_BLOCK kDO_LAMBDA].include?(expected_token[0])
+          when :tLPAREN
+            actual_token[0] = expected_token[0] if expected_token[0] == :tLPAREN2
+          when :tPOW
+            actual_token[0] = expected_token[0] if expected_token[0] == :tDSTAR
+          end
+
+          # Now we can assert that the tokens are actually equal.
+          assert_equal expected_token, actual_token, -> {
+            "expected: #{expected_token.inspect}\n" \
+            "actual: #{actual_token.inspect}"
+          }
+        end
+      end
+    end
+
+    def assert_equal_comments(expected_comments, actual_comments)
+      assert_equal expected_comments, actual_comments, -> {
+        "expected: #{expected_comments.inspect}\n" \
+        "actual: #{actual_comments.inspect}"
+      }
+    end
+  end
+end

test/prism/ruby/pattern_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class PatternTest < TestCase

test/prism/ruby/reflection_test.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class ReflectionTest < TestCase

test/prism/ruby/ripper_test.rb

@@ -2,13 +2,11 @@
 
 return if RUBY_VERSION < "3.3"
 
-require_relative "test_helper"
+require_relative "../test_helper"
 
 module Prism
   class RipperTest < TestCase
-    base = File.join(__dir__, "fixtures")
-    relatives = ENV["FOCUS"] ? [ENV["FOCUS"]] : Dir["**/*.txt", base: base]
-
+    # Skip these tests that Ripper is reporting the wrong results for.
     incorrect = [
       # Ripper incorrectly attributes the block to the keyword.
       "seattlerb/block_break.txt",
@@ -31,6 +29,7 @@ module Prism
       "spanning_heredoc.txt"
     ]
 
+    # Skip these tests that we haven't implemented yet.
     omitted = [
       "dos_endings.txt",
       "heredocs_with_ignored_newlines.txt",
@@ -50,30 +49,8 @@ module Prism
       "whitequark/slash_newline_in_heredocs.txt"
     ]
 
-    relatives.each do |relative|
-      # Skip the tests that Ripper is reporting the wrong results for.
-      next if incorrect.include?(relative)
-
-      # Skip the tests we haven't implemented yet.
-      next if omitted.include?(relative)
-
-      filepath = File.join(__dir__, "fixtures", relative)
-
-      define_method "test_ripper_#{relative}" do
-        source = File.read(filepath, binmode: true, external_encoding: Encoding::UTF_8)
-
-        case relative
-        when /break|next|redo|if|unless|rescue|control|keywords|retry/
-          source = "-> do\nrescue\n#{source}\nend"
-        end
-
-        case source
-        when /^ *yield/
-          source = "def __invalid_yield__\n#{source}\nend"
-        end
-
-        assert_ripper(source)
-      end
+    Fixture.each(except: incorrect | omitted) do |fixture|
+      define_method(fixture.test_name) { assert_ripper(fixture.read) }
     end
 
     private

test/prism/ruby/ruby_parser_test.rb

@@ -0,0 +1,127 @@
+# frozen_string_literal: true
+
+return if RUBY_ENGINE == "jruby"
+
+require_relative "../test_helper"
+
+begin
+  require "ruby_parser"
+rescue LoadError
+  # In CRuby's CI, we're not going to test against the ruby_parser gem because
+  # we don't want to have to install it. So in this case we'll just skip this
+  # test.
+  return
+end
+
+# We want to also compare lines and files to make sure we're setting them
+# correctly.
+Sexp.prepend(
+  Module.new do
+    def ==(other)
+      super && line == other.line && file == other.file # && line_max == other.line_max
+    end
+  end
+)
+
+module Prism
+  class RubyParserTest < TestCase
+    todos = [
+      "newline_terminated.txt",
+      "regex_char_width.txt",
+      "seattlerb/bug169.txt",
+      "seattlerb/masgn_colon3.txt",
+      "seattlerb/messy_op_asgn_lineno.txt",
+      "seattlerb/op_asgn_primary_colon_const_command_call.txt",
+      "seattlerb/regexp_esc_C_slash.txt",
+      "seattlerb/str_lit_concat_bad_encodings.txt",
+      "unescaping.txt",
+      "unparser/corpus/literal/kwbegin.txt",
+      "unparser/corpus/literal/send.txt",
+      "whitequark/masgn_const.txt",
+      "whitequark/ruby_bug_12402.txt",
+      "whitequark/ruby_bug_14690.txt",
+      "whitequark/space_args_block.txt"
+    ]
+
+    # https://github.com/seattlerb/ruby_parser/issues/344
+    failures = [
+      "alias.txt",
+      "dos_endings.txt",
+      "heredocs_with_ignored_newlines.txt",
+      "method_calls.txt",
+      "methods.txt",
+      "multi_write.txt",
+      "not.txt",
+      "patterns.txt",
+      "regex.txt",
+      "seattlerb/and_multi.txt",
+      "seattlerb/heredoc__backslash_dos_format.txt",
+      "seattlerb/heredoc_bad_hex_escape.txt",
+      "seattlerb/heredoc_bad_oct_escape.txt",
+      "seattlerb/heredoc_with_extra_carriage_horrible_mix.txt",
+      "seattlerb/heredoc_with_extra_carriage_returns_windows.txt",
+      "seattlerb/heredoc_with_only_carriage_returns_windows.txt",
+      "seattlerb/heredoc_with_only_carriage_returns.txt",
+      "spanning_heredoc_newlines.txt",
+      "spanning_heredoc.txt",
+      "tilde_heredocs.txt",
+      "unparser/corpus/literal/literal.txt",
+      "while.txt",
+      "whitequark/cond_eflipflop.txt",
+      "whitequark/cond_iflipflop.txt",
+      "whitequark/cond_match_current_line.txt",
+      "whitequark/dedenting_heredoc.txt",
+      "whitequark/lvar_injecting_match.txt",
+      "whitequark/not.txt",
+      "whitequark/numparam_ruby_bug_19025.txt",
+      "whitequark/op_asgn_cmd.txt",
+      "whitequark/parser_bug_640.txt",
+      "whitequark/parser_slash_slash_n_escaping_in_literals.txt",
+      "whitequark/pattern_matching_single_line_allowed_omission_of_parentheses.txt",
+      "whitequark/pattern_matching_single_line.txt",
+      "whitequark/ruby_bug_11989.txt",
+      "whitequark/slash_newline_in_heredocs.txt"
+    ]
+
+    Fixture.each(except: failures) do |fixture|
+      define_method(fixture.test_name) do
+        assert_ruby_parser(fixture, todos.include?(fixture.path))
+      end
+    end
+
+    private
+
+    def assert_ruby_parser(fixture, allowed_failure)
+      source = fixture.read
+      expected = ignore_warnings { ::RubyParser.new.parse(source, fixture.path) }
+      actual = Prism::Translation::RubyParser.new.parse(source, fixture.path)
+
+      if !allowed_failure
+        assert_equal(expected, actual, -> { message(expected, actual) })
+      elsif expected == actual
+        puts "#{name} now passes"
+      end
+    end
+
+    def message(expected, actual)
+      if expected == actual
+        nil
+      elsif expected.is_a?(Sexp) && actual.is_a?(Sexp)
+        if expected.line != actual.line
+          "expected: (#{expected.inspect} line=#{expected.line}), actual: (#{actual.inspect} line=#{actual.line})"
+        elsif expected.file != actual.file
+          "expected: (#{expected.inspect} file=#{expected.file}), actual: (#{actual.inspect} file=#{actual.file})"
+        elsif expected.length != actual.length
+          "expected: (#{expected.inspect} length=#{expected.length}), actual: (#{actual.inspect} length=#{actual.length})"
+        else
+          expected.zip(actual).find do |expected_field, actual_field|
+            result = message(expected_field, actual_field)
+            break result if result
+          end
+        end
+      else
+        "expected: #{expected.inspect}, actual: #{actual.inspect}"
+      end
+    end
+  end
+end

test/prism/ruby/tunnel_test.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+require_relative "../test_helper"
+
+module Prism
+  class TunnelTest < TestCase
+    def test_tunnel
+      program = Prism.parse("foo(1) +\n  bar(2, 3) +\n  baz(3, 4, 5)").value
+
+      tunnel = program.tunnel(1, 4).last
+      assert_kind_of IntegerNode, tunnel
+      assert_equal 1, tunnel.value
+
+      tunnel = program.tunnel(2, 6).last
+      assert_kind_of IntegerNode, tunnel
+      assert_equal 2, tunnel.value
+
+      tunnel = program.tunnel(3, 9).last
+      assert_kind_of IntegerNode, tunnel
+      assert_equal 4, tunnel.value
+
+      tunnel = program.tunnel(3, 8)
+      assert_equal [ProgramNode, StatementsNode, CallNode, ArgumentsNode, CallNode, ArgumentsNode], tunnel.map(&:class)
+    end
+  end
+end

test/prism/ruby_api_test.rb

@@ -1,307 +0,0 @@
-# frozen_string_literal: true
-
-require_relative "test_helper"
-
-module Prism
-  class RubyAPITest < TestCase
-    if !ENV["PRISM_BUILD_MINIMAL"]
-      def test_ruby_api
-        filepath = __FILE__
-        source = File.read(filepath, binmode: true, external_encoding: Encoding::UTF_8)
-
-        assert_equal Prism.lex(source, filepath: filepath).value, Prism.lex_file(filepath).value
-        assert_equal Prism.dump(source, filepath: filepath), Prism.dump_file(filepath)
-
-        serialized = Prism.dump(source, filepath: filepath)
-        ast1 = Prism.load(source, serialized).value
-        ast2 = Prism.parse(source, filepath: filepath).value
-        ast3 = Prism.parse_file(filepath).value
-
-        assert_equal_nodes ast1, ast2
-        assert_equal_nodes ast2, ast3
-      end
-    end
-
-    def test_parse_success?
-      assert Prism.parse_success?("1")
-      refute Prism.parse_success?("<>")
-    end
-
-    def test_parse_file_success?
-      assert Prism.parse_file_success?(__FILE__)
-    end
-
-    def test_options
-      assert_equal "", Prism.parse("__FILE__").value.statements.body[0].filepath
-      assert_equal "foo.rb", Prism.parse("__FILE__", filepath: "foo.rb").value.statements.body[0].filepath
-
-      assert_equal 1, Prism.parse("foo").value.statements.body[0].location.start_line
-      assert_equal 10, Prism.parse("foo", line: 10).value.statements.body[0].location.start_line
-
-      refute Prism.parse("\"foo\"").value.statements.body[0].frozen?
-      assert Prism.parse("\"foo\"", frozen_string_literal: true).value.statements.body[0].frozen?
-      refute Prism.parse("\"foo\"", frozen_string_literal: false).value.statements.body[0].frozen?
-
-      assert_kind_of Prism::CallNode, Prism.parse("foo").value.statements.body[0]
-      assert_kind_of Prism::LocalVariableReadNode, Prism.parse("foo", scopes: [[:foo]]).value.statements.body[0]
-      assert_equal 1, Prism.parse("foo", scopes: [[:foo], []]).value.statements.body[0].depth
-
-      assert_equal [:foo], Prism.parse("foo", scopes: [[:foo]]).value.locals
-    end
-
-    def test_literal_value_method
-      assert_equal 123, parse_expression("123").value
-      assert_equal 3.14, parse_expression("3.14").value
-      assert_equal 42i, parse_expression("42i").value
-      assert_equal 42.1ri, parse_expression("42.1ri").value
-      assert_equal 3.14i, parse_expression("3.14i").value
-      assert_equal 42r, parse_expression("42r").value
-      assert_equal 0.5r, parse_expression("0.5r").value
-      assert_equal 42ri, parse_expression("42ri").value
-      assert_equal 0.5ri, parse_expression("0.5ri").value
-      assert_equal 0xFFr, parse_expression("0xFFr").value
-      assert_equal 0xFFri, parse_expression("0xFFri").value
-    end
-
-    def test_location_join
-      recv, args_node, _ = parse_expression("1234 + 567").child_nodes
-      arg = args_node.arguments[0]
-
-      joined = recv.location.join(arg.location)
-      assert_equal 0, joined.start_offset
-      assert_equal 10, joined.length
-
-      assert_raise RuntimeError, "Incompatible locations" do
-        arg.location.join(recv.location)
-      end
-
-      other_arg = parse_expression("1234 + 567").arguments.arguments[0]
-
-      assert_raise RuntimeError, "Incompatible sources" do
-        other_arg.location.join(recv.location)
-      end
-
-      assert_raise RuntimeError, "Incompatible sources" do
-        recv.location.join(other_arg.location)
-      end
-    end
-
-    def test_location_character_offsets
-      program = Prism.parse("😀 + 😀\n😍 ||= 😍").value
-
-      # first 😀
-      location = program.statements.body.first.receiver.location
-      assert_equal 0, location.start_character_offset
-      assert_equal 1, location.end_character_offset
-      assert_equal 0, location.start_character_column
-      assert_equal 1, location.end_character_column
-
-      # second 😀
-      location = program.statements.body.first.arguments.arguments.first.location
-      assert_equal 4, location.start_character_offset
-      assert_equal 5, location.end_character_offset
-      assert_equal 4, location.start_character_column
-      assert_equal 5, location.end_character_column
-
-      # first 😍
-      location = program.statements.body.last.name_loc
-      assert_equal 6, location.start_character_offset
-      assert_equal 7, location.end_character_offset
-      assert_equal 0, location.start_character_column
-      assert_equal 1, location.end_character_column
-
-      # second 😍
-      location = program.statements.body.last.value.location
-      assert_equal 12, location.start_character_offset
-      assert_equal 13, location.end_character_offset
-      assert_equal 6, location.start_character_column
-      assert_equal 7, location.end_character_column
-    end
-
-    def test_location_code_units
-      program = Prism.parse("😀 + 😀\n😍 ||= 😍").value
-
-      # first 😀
-      location = program.statements.body.first.receiver.location
-
-      assert_equal 0, location.start_code_units_offset(Encoding::UTF_8)
-      assert_equal 0, location.start_code_units_offset(Encoding::UTF_16LE)
-      assert_equal 0, location.start_code_units_offset(Encoding::UTF_32LE)
-
-      assert_equal 1, location.end_code_units_offset(Encoding::UTF_8)
-      assert_equal 2, location.end_code_units_offset(Encoding::UTF_16LE)
-      assert_equal 1, location.end_code_units_offset(Encoding::UTF_32LE)
-
-      assert_equal 0, location.start_code_units_column(Encoding::UTF_8)
-      assert_equal 0, location.start_code_units_column(Encoding::UTF_16LE)
-      assert_equal 0, location.start_code_units_column(Encoding::UTF_32LE)
-
-      assert_equal 1, location.end_code_units_column(Encoding::UTF_8)
-      assert_equal 2, location.end_code_units_column(Encoding::UTF_16LE)
-      assert_equal 1, location.end_code_units_column(Encoding::UTF_32LE)
-
-      # second 😀
-      location = program.statements.body.first.arguments.arguments.first.location
-
-      assert_equal 4, location.start_code_units_offset(Encoding::UTF_8)
-      assert_equal 5, location.start_code_units_offset(Encoding::UTF_16LE)
-      assert_equal 4, location.start_code_units_offset(Encoding::UTF_32LE)
-
-      assert_equal 5, location.end_code_units_offset(Encoding::UTF_8)
-      assert_equal 7, location.end_code_units_offset(Encoding::UTF_16LE)
-      assert_equal 5, location.end_code_units_offset(Encoding::UTF_32LE)
-
-      assert_equal 4, location.start_code_units_column(Encoding::UTF_8)
-      assert_equal 5, location.start_code_units_column(Encoding::UTF_16LE)
-      assert_equal 4, location.start_code_units_column(Encoding::UTF_32LE)
-
-      assert_equal 5, location.end_code_units_column(Encoding::UTF_8)
-      assert_equal 7, location.end_code_units_column(Encoding::UTF_16LE)
-      assert_equal 5, location.end_code_units_column(Encoding::UTF_32LE)
-
-      # first 😍
-      location = program.statements.body.last.name_loc
-
-      assert_equal 6, location.start_code_units_offset(Encoding::UTF_8)
-      assert_equal 8, location.start_code_units_offset(Encoding::UTF_16LE)
-      assert_equal 6, location.start_code_units_offset(Encoding::UTF_32LE)
-
-      assert_equal 7, location.end_code_units_offset(Encoding::UTF_8)
-      assert_equal 10, location.end_code_units_offset(Encoding::UTF_16LE)
-      assert_equal 7, location.end_code_units_offset(Encoding::UTF_32LE)
-
-      assert_equal 0, location.start_code_units_column(Encoding::UTF_8)
-      assert_equal 0, location.start_code_units_column(Encoding::UTF_16LE)
-      assert_equal 0, location.start_code_units_column(Encoding::UTF_32LE)
-
-      assert_equal 1, location.end_code_units_column(Encoding::UTF_8)
-      assert_equal 2, location.end_code_units_column(Encoding::UTF_16LE)
-      assert_equal 1, location.end_code_units_column(Encoding::UTF_32LE)
-
-      # second 😍
-      location = program.statements.body.last.value.location
-
-      assert_equal 12, location.start_code_units_offset(Encoding::UTF_8)
-      assert_equal 15, location.start_code_units_offset(Encoding::UTF_16LE)
-      assert_equal 12, location.start_code_units_offset(Encoding::UTF_32LE)
-
-      assert_equal 13, location.end_code_units_offset(Encoding::UTF_8)
-      assert_equal 17, location.end_code_units_offset(Encoding::UTF_16LE)
-      assert_equal 13, location.end_code_units_offset(Encoding::UTF_32LE)
-
-      assert_equal 6, location.start_code_units_column(Encoding::UTF_8)
-      assert_equal 7, location.start_code_units_column(Encoding::UTF_16LE)
-      assert_equal 6, location.start_code_units_column(Encoding::UTF_32LE)
-
-      assert_equal 7, location.end_code_units_column(Encoding::UTF_8)
-      assert_equal 9, location.end_code_units_column(Encoding::UTF_16LE)
-      assert_equal 7, location.end_code_units_column(Encoding::UTF_32LE)
-    end
-
-    def test_location_chop
-      location = Prism.parse("foo").value.location
-
-      assert_equal "fo", location.chop.slice
-      assert_equal "", location.chop.chop.chop.slice
-
-      # Check that we don't go negative.
-      10.times { location = location.chop }
-      assert_equal "", location.slice
-    end
-
-    def test_location_slice_lines
-      result = Prism.parse("\nprivate def foo\nend\n")
-      method = result.value.statements.body.first.arguments.arguments.first
-
-      assert_equal "private def foo\nend\n", method.slice_lines
-    end
-
-    def test_heredoc?
-      refute parse_expression("\"foo\"").heredoc?
-      refute parse_expression("\"foo \#{1}\"").heredoc?
-      refute parse_expression("`foo`").heredoc?
-      refute parse_expression("`foo \#{1}`").heredoc?
-
-      assert parse_expression("<<~HERE\nfoo\nHERE\n").heredoc?
-      assert parse_expression("<<~HERE\nfoo \#{1}\nHERE\n").heredoc?
-      assert parse_expression("<<~`HERE`\nfoo\nHERE\n").heredoc?
-      assert parse_expression("<<~`HERE`\nfoo \#{1}\nHERE\n").heredoc?
-    end
-
-    # Through some bit hackery, we want to allow consumers to use the integer
-    # base flags as the base itself. It has a nice property that the current
-    # alignment provides them in the correct order. So here we test that our
-    # assumption holds so that it doesn't change out from under us.
-    #
-    # In C, this would look something like:
-    #
-    #     ((flags & ~DECIMAL) << 1) || 10
-    #
-    # We have to do some other work in Ruby because 0 is truthy and ~ on an
-    # integer doesn't have a fixed width.
-    def test_integer_base_flags
-      base = -> (node) do
-        value = (node.send(:flags) & (0b1111 - IntegerBaseFlags::DECIMAL)) << 1
-        value == 0 ? 10 : value
-      end
-
-      assert_equal 2, base[parse_expression("0b1")]
-      assert_equal 8, base[parse_expression("0o1")]
-      assert_equal 10, base[parse_expression("0d1")]
-      assert_equal 16, base[parse_expression("0x1")]
-    end
-
-    def test_node_equality
-      assert_operator parse_expression("1"), :===, parse_expression("1")
-      assert_operator Prism.parse("1").value, :===, Prism.parse("1").value
-
-      complex_source = "class Something; @var = something.else { _1 }; end"
-      assert_operator parse_expression(complex_source), :===, parse_expression(complex_source)
-
-      refute_operator parse_expression("1"), :===, parse_expression("2")
-      refute_operator parse_expression("1"), :===, parse_expression("0x1")
-
-      complex_source_1 = "class Something; @var = something.else { _1 }; end"
-      complex_source_2 = "class Something; @var = something.else { _2 }; end"
-      refute_operator parse_expression(complex_source_1), :===, parse_expression(complex_source_2)
-    end
-
-    def test_node_tunnel
-      program = Prism.parse("foo(1) +\n  bar(2, 3) +\n  baz(3, 4, 5)").value
-
-      tunnel = program.tunnel(1, 4).last
-      assert_kind_of IntegerNode, tunnel
-      assert_equal 1, tunnel.value
-
-      tunnel = program.tunnel(2, 6).last
-      assert_kind_of IntegerNode, tunnel
-      assert_equal 2, tunnel.value
-
-      tunnel = program.tunnel(3, 9).last
-      assert_kind_of IntegerNode, tunnel
-      assert_equal 4, tunnel.value
-
-      tunnel = program.tunnel(3, 8)
-      assert_equal [ProgramNode, StatementsNode, CallNode, ArgumentsNode, CallNode, ArgumentsNode], tunnel.map(&:class)
-    end
-
-    def test_location_adjoin
-      program = Prism.parse("foo.bar = 1").value
-
-      location = program.statements.body.first.message_loc
-      adjoined = location.adjoin("=")
-
-      assert_kind_of Location, adjoined
-      refute_equal location, adjoined
-
-      assert_equal 4, adjoined.start_offset
-      assert_equal 9, adjoined.end_offset
-    end
-
-    private
-
-    def parse_expression(source)
-      Prism.parse(source).value.statements.body.first
-    end
-  end
-end

test/prism/ruby_parser_test.rb

@@ -1,135 +0,0 @@
-# frozen_string_literal: true
-
-return if RUBY_ENGINE == "jruby"
-
-require_relative "test_helper"
-
-begin
-  require "ruby_parser"
-rescue LoadError
-  # In CRuby's CI, we're not going to test against the ruby_parser gem because
-  # we don't want to have to install it. So in this case we'll just skip this
-  # test.
-  return
-end
-
-# We want to also compare lines and files to make sure we're setting them
-# correctly.
-Sexp.prepend(
-  Module.new do
-    def ==(other)
-      super && line == other.line && line_max == other.line_max && file == other.file
-    end
-  end
-)
-
-module Prism
-  class RubyParserTest < TestCase
-    base = File.join(__dir__, "fixtures")
-
-    todos = %w[
-      newline_terminated.txt
-      regex_char_width.txt
-      seattlerb/bug169.txt
-      seattlerb/masgn_colon3.txt
-      seattlerb/messy_op_asgn_lineno.txt
-      seattlerb/op_asgn_primary_colon_const_command_call.txt
-      seattlerb/regexp_esc_C_slash.txt
-      seattlerb/str_lit_concat_bad_encodings.txt
-      unescaping.txt
-      unparser/corpus/literal/kwbegin.txt
-      unparser/corpus/literal/send.txt
-      whitequark/masgn_const.txt
-      whitequark/ruby_bug_12402.txt
-      whitequark/ruby_bug_14690.txt
-      whitequark/space_args_block.txt
-    ]
-
-    # https://github.com/seattlerb/ruby_parser/issues/344
-    failures = %w[
-      alias.txt
-      dos_endings.txt
-      heredocs_with_ignored_newlines.txt
-      method_calls.txt
-      methods.txt
-      multi_write.txt
-      not.txt
-      patterns.txt
-      regex.txt
-      seattlerb/and_multi.txt
-      seattlerb/heredoc__backslash_dos_format.txt
-      seattlerb/heredoc_bad_hex_escape.txt
-      seattlerb/heredoc_bad_oct_escape.txt
-      seattlerb/heredoc_with_extra_carriage_horrible_mix.txt
-      seattlerb/heredoc_with_extra_carriage_returns_windows.txt
-      seattlerb/heredoc_with_only_carriage_returns_windows.txt
-      seattlerb/heredoc_with_only_carriage_returns.txt
-      spanning_heredoc_newlines.txt
-      spanning_heredoc.txt
-      tilde_heredocs.txt
-      unparser/corpus/literal/literal.txt
-      while.txt
-      whitequark/cond_eflipflop.txt
-      whitequark/cond_iflipflop.txt
-      whitequark/cond_match_current_line.txt
-      whitequark/dedenting_heredoc.txt
-      whitequark/lvar_injecting_match.txt
-      whitequark/not.txt
-      whitequark/numparam_ruby_bug_19025.txt
-      whitequark/op_asgn_cmd.txt
-      whitequark/parser_bug_640.txt
-      whitequark/parser_slash_slash_n_escaping_in_literals.txt
-      whitequark/pattern_matching_single_line_allowed_omission_of_parentheses.txt
-      whitequark/pattern_matching_single_line.txt
-      whitequark/ruby_bug_11989.txt
-      whitequark/slash_newline_in_heredocs.txt
-    ]
-
-    Dir["**/*.txt", base: base].each do |name|
-      next if failures.include?(name)
-
-      define_method("test_#{name}") do
-        begin
-          # Parsing with ruby parser tends to be noisy with warnings, so we're
-          # turning those off.
-          previous_verbose, $VERBOSE = $VERBOSE, nil
-          assert_parse_file(base, name, todos.include?(name))
-        ensure
-          $VERBOSE = previous_verbose
-        end
-      end
-    end
-
-    private
-
-    def assert_parse_file(base, name, allowed_failure)
-      filepath = File.join(base, name)
-      expected = ::RubyParser.new.parse(File.read(filepath), filepath)
-      actual = Prism::Translation::RubyParser.parse_file(filepath)
-
-      if !allowed_failure
-        assert_equal_nodes expected, actual
-      elsif expected == actual
-        puts "#{name} now passes"
-      end
-    end
-
-    def assert_equal_nodes(left, right)
-      return if left == right
-
-      if left.is_a?(Sexp) && right.is_a?(Sexp)
-        if left.line != right.line
-          assert_equal "(#{left.inspect} line=#{left.line})", "(#{right.inspect} line=#{right.line})"
-        elsif left.file != right.file
-          assert_equal "(#{left.inspect} file=#{left.file})", "(#{right.inspect} file=#{right.file})"
-        elsif left.length != right.length
-          assert_equal "(#{left.inspect} length=#{left.length})", "(#{right.inspect} length=#{right.length})"
-        else
-          left.zip(right).each { |l, r| assert_equal_nodes(l, r) }
-        end
-      else
-        assert_equal left, right
-      end
-    end
-  end
-end

test/prism/snapshots_test.rb

@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+require_relative "test_helper"
+
+module Prism
+  class SnapshotsTest < TestCase
+    # When we pretty-print the trees to compare against the snapshots, we want
+    # to be certain that we print with the same external encoding. This is
+    # because methods like Symbol#inspect take into account external encoding
+    # and it could change how the snapshot is generated. On machines with
+    # certain settings (like LANG=C or -Eascii-8bit) this could have been
+    # changed. So here we're going to force it to be UTF-8 to keep the snapshots
+    # consistent.
+    def setup
+      @previous_default_external = Encoding.default_external
+      ignore_warnings { Encoding.default_external = Encoding::UTF_8 }
+    end
+
+    def teardown
+      ignore_warnings { Encoding.default_external = @previous_default_external }
+    end
+
+    except = []
+
+    # These fail on TruffleRuby due to a difference in Symbol#inspect:
+    # :测试 vs :"测试"
+    if RUBY_ENGINE == "truffleruby"
+      except.push(
+        "emoji_method_calls.txt",
+        "seattlerb/bug202.txt",
+        "seattlerb/magic_encoding_comment.txt"
+      )
+    end
+
+    Fixture.each(except: except) do |fixture|
+      define_method(fixture.test_name) { assert_snapshot(fixture) }
+    end
+
+    private
+
+    def assert_snapshot(fixture)
+      source = fixture.read
+
+      result = Prism.parse(source, filepath: fixture.path)
+      assert result.success?
+
+      printed = PP.pp(result.value, +"", 79)
+      snapshot = fixture.snapshot_path
+
+      if File.exist?(snapshot)
+        saved = File.read(snapshot)
+
+        # If the snapshot file exists, but the printed value does not match the
+        # snapshot, then update the snapshot file.
+        if printed != saved
+          File.write(snapshot, printed)
+          warn("Updated snapshot at #{snapshot}.")
+        end
+
+        # If the snapshot file exists, then assert that the printed value
+        # matches the snapshot.
+        assert_equal(saved, printed)
+      else
+        # If the snapshot file does not yet exist, then write it out now.
+        directory = File.dirname(snapshot)
+        FileUtils.mkdir_p(directory) unless File.directory?(directory)
+
+        File.write(snapshot, printed)
+        warn("Created snapshot at #{snapshot}.")
+      end
+    end
+  end
+end

test/prism/snippets_test.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+require_relative "test_helper"
+
+module Prism
+  class SnippetsTest < TestCase
+    except = [
+      "newline_terminated.txt",
+      "seattlerb/begin_rescue_else_ensure_no_bodies.txt",
+      "seattlerb/case_in.txt",
+      "seattlerb/parse_line_defn_no_parens.txt",
+      "seattlerb/pct_nl.txt",
+      "seattlerb/str_heredoc_interp.txt",
+      "spanning_heredoc_newlines.txt",
+      "unparser/corpus/semantic/dstr.txt",
+      "whitequark/dedenting_heredoc.txt",
+      "whitequark/multiple_pattern_matches.txt"
+    ]
+
+    Fixture.each(except: except) do |fixture|
+      define_method(fixture.test_name) { assert_snippets(fixture) }
+    end
+
+    private
+
+    # We test every snippet (separated by \n\n) in isolation to ensure the
+    # parser does not try to read bytes further than the end of each snippet.
+    def assert_snippets(fixture)
+      fixture.read.split(/(?<=\S)\n\n(?=\S)/).each do |snippet|
+        snippet = snippet.rstrip
+
+        result = Prism.parse(snippet, filepath: fixture.path)
+        assert result.success?
+
+        if !ENV["PRISM_BUILD_MINIMAL"]
+          dumped = Prism.dump(snippet, filepath: fixture.path)
+          assert_equal_nodes(result.value, Prism.load(snippet, dumped).value)
+        end
+      end
+    end
+  end
+end

test/prism/test_helper.rb

@@ -1,8 +1,9 @@
 # frozen_string_literal: true
 
 require "prism"
-require "ripper"
 require "pp"
+require "ripper"
+require "stringio"
 require "test/unit"
 require "tempfile"
 
@@ -16,19 +17,202 @@ if defined?(Test::Unit::Assertions::AssertionMessage)
 end
 
 module Prism
+  # A convenience method for retrieving the first statement in the source string
+  # parsed by Prism.
+  def self.parse_statement(source, **options)
+    parse(source, **options).value.statements.body.first
+  end
+
+  class ParseResult < Result
+    # Returns the first statement in the body of the parsed source.
+    def statement
+      value.statements.body.first
+    end
+  end
+
   class TestCase < ::Test::Unit::TestCase
+    # We have a set of fixtures that we use to test various aspects of the
+    # parser. They are all represented as .txt files under the
+    # test/prism/fixtures directory. Typically in test files you will find calls
+    # to Fixture.each which yields Fixture objects to the given block. These
+    # are used to define test methods that assert against each fixture in some
+    # way.
+    class Fixture
+      BASE = File.join(__dir__, "fixtures")
+
+      attr_reader :path
+
+      def initialize(path)
+        @path = path
+      end
+
+      def read
+        File.read(full_path, binmode: true, external_encoding: Encoding::UTF_8)
+      end
+
+      def full_path
+        File.join(BASE, path)
+      end
+
+      def snapshot_path
+        File.join(__dir__, "snapshots", path)
+      end
+
+      def test_name
+        :"test_#{path}"
+      end
+
+      def self.each(except: [], &block)
+        paths = Dir[ENV.fetch("FOCUS") { File.join("**", "*.txt") }, base: BASE] - except
+        paths.each { |path| yield Fixture.new(path) }
+      end
+    end
+
+    # Yield each encoding that we want to test, along with a range of the
+    # codepoints that should be tested.
+    def self.each_encoding
+      codepoints_1byte = 0...0x100
+
+      yield Encoding::ASCII_8BIT, codepoints_1byte
+      yield Encoding::US_ASCII, codepoints_1byte
+
+      if !ENV["PRISM_BUILD_MINIMAL"]
+        yield Encoding::Windows_1253, codepoints_1byte
+      end
+
+      # By default we don't test every codepoint in these encodings because it
+      # takes a very long time.
+      return unless ENV["PRISM_TEST_ALL_ENCODINGS"]
+
+      yield Encoding::CP850, codepoints_1byte
+      yield Encoding::CP852, codepoints_1byte
+      yield Encoding::CP855, codepoints_1byte
+      yield Encoding::GB1988, codepoints_1byte
+      yield Encoding::IBM437, codepoints_1byte
+      yield Encoding::IBM720, codepoints_1byte
+      yield Encoding::IBM737, codepoints_1byte
+      yield Encoding::IBM775, codepoints_1byte
+      yield Encoding::IBM852, codepoints_1byte
+      yield Encoding::IBM855, codepoints_1byte
+      yield Encoding::IBM857, codepoints_1byte
+      yield Encoding::IBM860, codepoints_1byte
+      yield Encoding::IBM861, codepoints_1byte
+      yield Encoding::IBM862, codepoints_1byte
+      yield Encoding::IBM863, codepoints_1byte
+      yield Encoding::IBM864, codepoints_1byte
+      yield Encoding::IBM865, codepoints_1byte
+      yield Encoding::IBM866, codepoints_1byte
+      yield Encoding::IBM869, codepoints_1byte
+      yield Encoding::ISO_8859_1, codepoints_1byte
+      yield Encoding::ISO_8859_2, codepoints_1byte
+      yield Encoding::ISO_8859_3, codepoints_1byte
+      yield Encoding::ISO_8859_4, codepoints_1byte
+      yield Encoding::ISO_8859_5, codepoints_1byte
+      yield Encoding::ISO_8859_6, codepoints_1byte
+      yield Encoding::ISO_8859_7, codepoints_1byte
+      yield Encoding::ISO_8859_8, codepoints_1byte
+      yield Encoding::ISO_8859_9, codepoints_1byte
+      yield Encoding::ISO_8859_10, codepoints_1byte
+      yield Encoding::ISO_8859_11, codepoints_1byte
+      yield Encoding::ISO_8859_13, codepoints_1byte
+      yield Encoding::ISO_8859_14, codepoints_1byte
+      yield Encoding::ISO_8859_15, codepoints_1byte
+      yield Encoding::ISO_8859_16, codepoints_1byte
+      yield Encoding::KOI8_R, codepoints_1byte
+      yield Encoding::KOI8_U, codepoints_1byte
+      yield Encoding::MACCENTEURO, codepoints_1byte
+      yield Encoding::MACCROATIAN, codepoints_1byte
+      yield Encoding::MACCYRILLIC, codepoints_1byte
+      yield Encoding::MACGREEK, codepoints_1byte
+      yield Encoding::MACICELAND, codepoints_1byte
+      yield Encoding::MACROMAN, codepoints_1byte
+      yield Encoding::MACROMANIA, codepoints_1byte
+      yield Encoding::MACTHAI, codepoints_1byte
+      yield Encoding::MACTURKISH, codepoints_1byte
+      yield Encoding::MACUKRAINE, codepoints_1byte
+      yield Encoding::TIS_620, codepoints_1byte
+      yield Encoding::Windows_1250, codepoints_1byte
+      yield Encoding::Windows_1251, codepoints_1byte
+      yield Encoding::Windows_1252, codepoints_1byte
+      yield Encoding::Windows_1254, codepoints_1byte
+      yield Encoding::Windows_1255, codepoints_1byte
+      yield Encoding::Windows_1256, codepoints_1byte
+      yield Encoding::Windows_1257, codepoints_1byte
+      yield Encoding::Windows_1258, codepoints_1byte
+      yield Encoding::Windows_874, codepoints_1byte
+
+      codepoints_2bytes = 0...0x10000
+
+      yield Encoding::Big5, codepoints_2bytes
+      yield Encoding::Big5_HKSCS, codepoints_2bytes
+      yield Encoding::Big5_UAO, codepoints_2bytes
+      yield Encoding::CP949, codepoints_2bytes
+      yield Encoding::CP950, codepoints_2bytes
+      yield Encoding::CP951, codepoints_2bytes
+      yield Encoding::EUC_KR, codepoints_2bytes
+      yield Encoding::GBK, codepoints_2bytes
+      yield Encoding::GB12345, codepoints_2bytes
+      yield Encoding::GB2312, codepoints_2bytes
+      yield Encoding::MACJAPANESE, codepoints_2bytes
+      yield Encoding::Shift_JIS, codepoints_2bytes
+      yield Encoding::SJIS_DoCoMo, codepoints_2bytes
+      yield Encoding::SJIS_KDDI, codepoints_2bytes
+      yield Encoding::SJIS_SoftBank, codepoints_2bytes
+      yield Encoding::Windows_31J, codepoints_2bytes
+
+      codepoints_unicode = (0...0x110000)
+
+      yield Encoding::UTF_8, codepoints_unicode
+      yield Encoding::UTF8_MAC, codepoints_unicode
+      yield Encoding::UTF8_DoCoMo, codepoints_unicode
+      yield Encoding::UTF8_KDDI, codepoints_unicode
+      yield Encoding::UTF8_SoftBank, codepoints_unicode
+      yield Encoding::CESU_8, codepoints_unicode
+
+      codepoints_eucjp = [
+        *(0...0x10000),
+        *(0...0x10000).map { |bytes| bytes | 0x8F0000 }
+      ]
+
+      yield Encoding::CP51932, codepoints_eucjp
+      yield Encoding::EUC_JP, codepoints_eucjp
+      yield Encoding::EUCJP_MS, codepoints_eucjp
+      yield Encoding::EUC_JIS_2004, codepoints_eucjp
+
+      codepoints_emacs_mule = [
+        *(0...0x80),
+        *((0x81...0x90).flat_map { |byte1| (0x90...0x100).map { |byte2| byte1 << 8 | byte2 } }),
+        *((0x90...0x9C).flat_map { |byte1| (0xA0...0x100).flat_map { |byte2| (0xA0...0x100).flat_map { |byte3| byte1 << 16 | byte2 << 8 | byte3 } } }),
+        *((0xF0...0xF5).flat_map { |byte2| (0xA0...0x100).flat_map { |byte3| (0xA0...0x100).flat_map { |byte4| 0x9C << 24 | byte3 << 16 | byte3 << 8 | byte4 } } }),
+      ]
+
+      yield Encoding::EMACS_MULE, codepoints_emacs_mule
+      yield Encoding::STATELESS_ISO_2022_JP, codepoints_emacs_mule
+      yield Encoding::STATELESS_ISO_2022_JP_KDDI, codepoints_emacs_mule
+
+      codepoints_gb18030 = [
+        *(0...0x80),
+        *((0x81..0xFE).flat_map { |byte1| (0x40...0x100).map { |byte2| byte1 << 8 | byte2 } }),
+        *((0x81..0xFE).flat_map { |byte1| (0x30...0x40).flat_map { |byte2| (0x81..0xFE).flat_map { |byte3| (0x2F...0x41).map { |byte4| byte1 << 24 | byte2 << 16 | byte3 << 8 | byte4 } } } }),
+      ]
+
+      yield Encoding::GB18030, codepoints_gb18030
+
+      codepoints_euc_tw = [
+        *(0..0x7F),
+        *(0xA1..0xFF).flat_map { |byte1| (0xA1..0xFF).map { |byte2| (byte1 << 8) | byte2 } },
+        *(0xA1..0xB0).flat_map { |byte2| (0xA1..0xFF).flat_map { |byte3| (0xA1..0xFF).flat_map { |byte4| 0x8E << 24 | byte2 << 16 | byte3 << 8 | byte4 } } }
+      ]
+
+      yield Encoding::EUC_TW, codepoints_euc_tw
+    end
+
     private
 
     if RUBY_ENGINE == "ruby"
       # Check that the given source is valid syntax by compiling it with RubyVM.
       def check_syntax(source)
-        $VERBOSE, previous = nil, $VERBOSE
-
-        begin
-          RubyVM::InstructionSequence.compile(source)
-        ensure
-          $VERBOSE = previous
-        end
+        ignore_warnings { RubyVM::InstructionSequence.compile(source) }
       end
 
       # Assert that the given source is valid Ruby syntax by attempting to
@@ -51,6 +235,8 @@ module Prism
       end
     end
 
+    # CRuby has this same method, so define it so that we don't accidentally
+    # break CRuby CI.
     def assert_raises(*args, &block)
       raise "Use assert_raise instead"
     end
@@ -122,5 +308,16 @@ module Prism
         assert_equal expected, actual
       end
     end
+
+    def ignore_warnings
+      previous = $VERBOSE
+      $VERBOSE = nil
+
+      begin
+        yield
+      ensure
+        $VERBOSE = previous
+      end
+    end
   end
 end

test/prism/unescape_test.rb

@@ -2,7 +2,7 @@
 
 require_relative "test_helper"
 
-return if RUBY_VERSION < "3.1.0" || Prism::BACKEND == :FFI
+return if RUBY_VERSION < "3.1.0"
 
 module Prism
   class UnescapeTest < TestCase
@@ -41,7 +41,7 @@ module Prism
           result = Prism.parse(code(escape), encoding: "binary")
 
           if result.success?
-            yield result.value.statements.body.first
+            yield result.statement
           else
             :error
           end