Add test file finder for ruby files

lib/quality/test_file_finder.rb

+# frozen_string_literal: true
+
+require 'ostruct'
+
+module Quality
+  class TestFileFinder
+    RUBY_EXTENSION = '.rb'
+    EE_PREFIX = 'ee/'
+
+    def initialize(file, foss_test_only: false)
+      @file = file
+      @foss_test_only = foss_test_only
+    end
+
+    def test_files
+      contexts = [ee_context, foss_context]
+      contexts.flat_map do |context|
+        match_test_files_for(context)
+      end
+    end
+
+    private
+
+    attr_reader :file, :foss_test_only
+
+    def ee_context
+      OpenStruct.new.tap do |ee|
+        ee.app = %r{^#{EE_PREFIX}app/(.+)\.rb$} unless foss_test_only
+        ee.lib = %r{^#{EE_PREFIX}lib/(.+)\.rb$} unless foss_test_only
+        ee.spec_dir = "#{EE_PREFIX}spec" unless foss_test_only
+        ee.ee_modules = %r{^#{EE_PREFIX}(.*\/)ee/(.+)\.rb$}
+        ee.foss_spec_dir = 'spec'
+      end
+    end
+
+    def foss_context
+      OpenStruct.new.tap do |foss|
+        foss.app = %r{^app/(.+)\.rb$}
+        foss.lib = %r{^lib/(.+)\.rb$}
+        foss.spec_dir = 'spec'
+      end
+    end
+
+    def match_test_files_for(context)
+      test_files = []
+
+      if (match = context.app&.match(file))
+        test_files << "#{context.spec_dir}/#{match[1]}_spec.rb"
+      end
+
+      if (match = context.lib&.match(file))
+        test_files << "#{context.spec_dir}/lib/#{match[1]}_spec.rb"
+      end
+
+      if (match = context.ee_modules&.match(file))
+        test_files << "#{context.foss_spec_dir}/#{match[1]}#{match[2]}_spec.rb"
+      end
+
+      test_files
+    end
+  end
+end

spec/lib/quality/test_file_finder_spec.rb

+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+
+describe Quality::TestFileFinder do
+  let(:file) { 'app/finders/admin/projects_finder.rb' }
+  let(:test_files) { ['spec/finders/admin/projects_finder_spec.rb'] }
+
+  subject { Quality::TestFileFinder.new(file) }
+
+  shared_examples 'finding matching test files' do
+    it 'returns matching test files' do
+      expect(subject.test_files).to match_array(test_files)
+    end
+  end
+
+  shared_examples 'not finding a matching test file' do
+    it 'returns empty array' do
+      expect(subject.test_files).to be_empty
+    end
+  end
+
+  describe '#test_files' do
+    it_behaves_like 'finding matching test files'
+
+    context 'when given non .rb files' do
+      let(:file) { 'app/assets/images/emoji.png' }
+
+      it_behaves_like 'not finding a matching test file'
+    end
+
+    context 'when given file in app/' do
+      let(:file) { 'app/finders/admin/projects_finder.rb' }
+      let(:test_files) { ['spec/finders/admin/projects_finder_spec.rb'] }
+
+      it_behaves_like 'finding matching test files'
+    end
+
+    context 'when given file in lib/' do
+      let(:file) { 'lib/banzai/color_parser.rb' }
+      let(:test_files) { ['spec/lib/banzai/color_parser_spec.rb'] }
+
+      it_behaves_like 'finding matching test files'
+    end
+
+    context 'when given a test file' do
+      let(:file) { 'spec/lib/banzai/color_parser_spec.rb' }
+
+      it_behaves_like 'not finding a matching test file'
+    end
+
+    context 'when given an ee app file' do
+      let(:file) { 'ee/app/models/analytics/cycle_analytics/group_level.rb' }
+      let(:test_files) { ['ee/spec/models/analytics/cycle_analytics/group_level_spec.rb'] }
+
+      it_behaves_like 'finding matching test files'
+    end
+
+    context 'when given an ee module file' do
+      let(:file) { 'ee/app/models/ee/user.rb' }
+      let(:test_files) { ['spec/app/models/user_spec.rb', 'ee/spec/models/ee/user_spec.rb'] }
+
+      it_behaves_like 'finding matching test files'
+    end
+
+    context 'when given an ee lib file' do
+      let(:file) { 'ee/lib/flipper_session.rb' }
+      let(:test_files) { ['ee/spec/lib/flipper_session_spec.rb'] }
+
+      it_behaves_like 'finding matching test files'
+    end
+
+    context 'when given an ee test file' do
+      let(:file) { 'ee/spec/lib/banzai/color_parser_spec.rb' }
+
+      it_behaves_like 'not finding a matching test file'
+    end
+
+    context 'with foss_test_only: true' do
+      let(:file) { 'ee/app/models/ee/user.rb' }
+      let(:test_files) { ['spec/app/models/user_spec.rb'] }
+
+      subject { Quality::TestFileFinder.new(file, foss_test_only: true) }
+
+      it 'excludes matching ee test files' do
+        expect(subject.test_files).to match_array(test_files)
+      end
+    end
+  end
+end