Add stackprof profiling to test suite.

To use, run STACKPROF=1 bundle exec rspec

Gemfile

@@ -6,3 +6,7 @@ gemspec
 
 # Whitelisted plugins not included in runtime dependencies.
 gem "jekyll-octicons"
+
+group :profile do
+  gem "stackprof", require: false
+end

spec/spec_helper.rb

@@ -2,6 +2,7 @@
 
 require File.expand_path("../lib/github-pages.rb", __dir__)
 require "open3"
+require_relative "spec_profiling"
 
 RSpec.configure do |config|
   config.run_all_when_everything_filtered = true
@@ -19,7 +20,7 @@ def fixture_dir
 end
 
 def tmp_dir
-  File.expand_path "../tmp", __dir__
+  File.expand_path "spec/tmp", __dir__
 end
 
 RSpec::Matchers.define :be_an_existing_file do

spec/spec_profiling.rb

@@ -0,0 +1,81 @@
+# Source: https://gist.github.com/palkan/73395cc201a565ecd3ff61aac44ad5ae
+
+module SpecProfiling
+  class << self
+    def init
+      ruby_prof if ENV['RUBYPROF']
+      stack_prof if ENV['STACKPROF']
+    end
+
+    def ruby_prof
+      require 'ruby-prof'
+      $stdout.puts "RubyProf enabled"
+
+      profiler = RubyProf::Profile.new(
+        merge_fibers: true,
+        include_threads: [Thread.current]
+      )
+
+      profiler.start
+
+      at_exit do
+        result = profiler.stop
+
+        # Common RSpec methods
+        result.eliminate_methods!(
+          [
+            /instance_exec/,
+            /Example(Group)?>?#run(_examples)?/,
+            /Procsy/,
+            /AroundHook#execute_with/,
+            /HookCollections/,
+            /Array#(map|each)/
+          ]
+        )
+        printer_type = ENV['RPRINTER'] || 'call_stack'
+        printer = "RubyProf::#{printer_type.camelize}Printer".constantize
+        path = File.join("tmp", "ruby-prof-report-#{printer_type}-#{RubyProf.measure_mode}-total.html")
+        File.open(path.to_s, 'w') { |f| printer.new(result).print(f, min_percent: 1) }
+      end
+    end
+
+    def stack_prof
+      require 'stackprof'
+      mode = ENV['RMODE'] || 'wall'
+      $stdout.puts "StackProf enabled (mode: #{mode})"
+      path = File.join("tmp", "stackprof-#{mode}-test-total.dump")
+      # we use raw to make it possible to generate flamegraphs
+      StackProf.start(mode: mode.to_sym, raw: true)
+
+      at_exit do
+        StackProf.stop
+        StackProf.results path.to_s
+      end
+    end
+  end
+end
+
+RSpec.configure do |config|
+  config.around(:each, :sprof) do |ex|
+    require 'stackprof'
+    mode = ENV['RMODE'] || 'wall'
+    path = File.join("tmp", "stackprof-#{mode}-test-#{ex.full_description.parameterize}.dump")
+    StackProf.run(mode: mode, out: path.to_s, raw: true) do
+      ex.run
+    end
+  end
+
+  config.around(:each, :rprof) do |ex|
+    require 'ruby-prof'
+
+    result = RubyProf.profile { ex.run }
+
+    printer_type = ENV['RPRINTER'] || 'call_stack'
+    printer = "RubyProf::#{printer_type.camelize}Printer".constantize
+
+    path = File.join("tmp", "ruby-prof-report-#{printer_type}-#{RubyProf.measure_mode}-#{ex.full_description.parameterize}.html")
+    File.open(path.to_s, 'w') { |f| printer.new(result).print(f, min_percent: 1) }
+  end
+end
+
+SpecProfiling.init