1 files changed, 68 insertions, 11 deletions
diff --git a/tooling/bin/find_changes b/tooling/bin/find_changes
index 20df085879a..c6b8bafbd85 100755
--- a/tooling/bin/find_changes
+++ b/tooling/bin/find_changes
@@ -3,19 +3,76 @@
 
 require 'gitlab'
 
-gitlab_token = ENV.fetch('PROJECT_TOKEN_FOR_CI_SCRIPTS_API_USAGE', '')
-gitlab_endpoint = ENV.fetch('CI_API_V4_URL')
-mr_project_path = ENV.fetch('CI_MERGE_REQUEST_PROJECT_PATH')
-mr_iid = ENV.fetch('CI_MERGE_REQUEST_IID')
+class FindChanges # rubocop:disable Gitlab/NamespacedClass
+  def initialize(output_file:, matched_tests_file: nil, frontend_fixtures_mapping_path: nil)
+    @gitlab_token = ENV.fetch('PROJECT_TOKEN_FOR_CI_SCRIPTS_API_USAGE', '')
+    @gitlab_endpoint = ENV.fetch('CI_API_V4_URL')
+    @mr_project_path = ENV.fetch('CI_MERGE_REQUEST_PROJECT_PATH')
+    @mr_iid = ENV.fetch('CI_MERGE_REQUEST_IID')
+    @output_file = output_file
+    @matched_tests_file = matched_tests_file
+    @frontend_fixtures_mapping_path = frontend_fixtures_mapping_path
+  end
 
-output_file = ARGV.shift
+  def execute
+    add_frontend_fixture_files!
+
+    File.write(output_file, file_changes.join(' '))
+  end
+
+  private
+
+  def add_frontend_fixture_files?
+    matched_tests_file && frontend_fixtures_mapping_path
+  end
+
+  def add_frontend_fixture_files!
+    return unless add_frontend_fixture_files?
+
+    # If we have a `test file -> JSON frontend fixture` mapping file, we add the files JSON frontend fixtures
+    # files to the list of changed files so that Jest can automatically run the dependent tests thanks to --findRelatedTests
+    test_files.each do |test_file|
+      file_changes.concat(frontend_fixtures_mapping[test_file]) if frontend_fixtures_mapping.key?(test_file)
+    end
+  end
+
+  def file_changes
+    @file_changes ||=
+      if File.exist?(output_file)
+        File.read(output_file).split(' ')
+      else
+        Gitlab.configure do |config|
+          config.endpoint      = gitlab_endpoint
+          config.private_token = gitlab_token
+        end
+
+        mr_changes = Gitlab.merge_request_changes(mr_project_path, mr_iid)
 
-Gitlab.configure do |config|
-  config.endpoint       = gitlab_endpoint
-  config.private_token  = gitlab_token
+        mr_changes.changes.map { |change| change['new_path'] }
+      end
+  end
+
+  def test_files
+    return [] if !matched_tests_file || !File.exist?(matched_tests_file)
+
+    File.read(matched_tests_file).split(' ')
+  end
+
+  def frontend_fixtures_mapping
+    return {} if !frontend_fixtures_mapping_path || !File.exist?(frontend_fixtures_mapping_path)
+
+    JSON.parse(File.read(frontend_fixtures_mapping_path)) # rubocop:disable Gitlab/Json
+  end
+
+  attr_reader :gitlab_token, :gitlab_endpoint, :mr_project_path, :mr_iid, :output_file, :matched_tests_file, :frontend_fixtures_mapping_path
 end
 
-mr_changes = Gitlab.merge_request_changes(mr_project_path, mr_iid)
-file_changes = mr_changes.changes.map { |change| change['new_path'] }
+output_file = ARGV.shift
+raise ArgumentError, "An path to an output file must be given as first argument of #{__FILE__}." if output_file.nil?
+
+matched_tests_file = ARGV.shift
+frontend_fixtures_mapping_path = ARGV.shift
 
-File.write(output_file, file_changes.join(' '))
+FindChanges
+  .new(output_file: output_file, matched_tests_file: matched_tests_file, frontend_fixtures_mapping_path: frontend_fixtures_mapping_path)
+  .execute