erb.rb: warn invalid trim_mode [Misc #15294]

From: Justin Collins <justin@presidentbeef.com>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65671 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/erb.rb

@@ -665,9 +665,13 @@ class ERB
         return [false, '>']
       when 2
         return [false, '<>']
-      when 0
+      when 0, nil
         return [false, nil]
       when String
+        unless mode.match?(/\A(%|-|>|<>){1,2}\z/)
+          warn_invalid_trim_mode(mode, uplevel: 5)
+        end
+
         perc = mode.include?('%')
         if mode.include?('-')
           return [perc, '-']
@@ -679,6 +683,7 @@ class ERB
           [perc, nil]
         end
       else
+        warn_invalid_trim_mode(mode, uplevel: 5)
         return [false, nil]
       end
     end
@@ -730,6 +735,10 @@ class ERB
       end
       return enc, frozen
     end
+
+    def warn_invalid_trim_mode(mode, uplevel:)
+      warn "Invalid ERB trim mode: #{mode.inspect} (trim_mode: nil, 0, 1, 2, or String composed of '%' and/or '-', '>', '<>')", uplevel: uplevel + 1
+    end
   end
 end
 

test/erb/test_erb.rb

@@ -235,6 +235,28 @@ EOS
     assert_equal("line\r\n" * 3, erb.result)
   end
 
+  def test_invalid_trim_mode
+    assert_warning(/#{__FILE__}:#{__LINE__ + 1}/) do
+      @erb.new("", trim_mode: 'abc-def')
+    end
+
+    assert_warning(/Invalid ERB trim mode/) do
+      @erb.new("", trim_mode: 'abc-def')
+    end
+
+    assert_warning(/Invalid ERB trim mode/) do
+      @erb.new("", trim_mode: '%<')
+    end
+
+    assert_warning(/Invalid ERB trim mode/) do
+      @erb.new("", trim_mode: '%<>-')
+    end
+
+    assert_warning(/Invalid ERB trim mode/) do
+      @erb.new("", trim_mode: 3)
+    end
+  end
+
   def test_run
     out = StringIO.new
     orig, $stdout = $stdout, out