E2E test: generate and edit commit message

qa/qa/ee/page/merge_request/show.rb

@@ -247,6 +247,15 @@ def verify_approved
             find_element('approve-button', text: "Revoke approval")
           end
 
+          def generate_commit
+            click_button('Generate commit message')
+            click_button('Insert')
+          end
+
+          def commit_message
+            find('#merge-message-edit').value
+          end
+
           private
 
           def approvals_content

qa/qa/page/merge_request/show.rb

@@ -90,6 +90,10 @@ class Show < Page::Base
           element 'squash-checkbox'
         end
 
+        view 'app/assets/javascripts/vue_merge_request_widget/components/states/ready_to_merge.vue' do
+          element 'widget_edit_commit_message'
+        end
+
         view 'app/assets/javascripts/vue_merge_request_widget/mr_widget_options.vue' do
           element 'mr-widget-content'
           element 'pipeline-container'
@@ -296,6 +300,10 @@ def mark_to_squash
           check_element('squash-checkbox', true)
         end
 
+        def edit_commit_message
+          check_element('widget_edit_commit_message', true)
+        end
+
         def merge!
           try_to_merge!
           finished_loading?

qa/qa/specs/features/ee/browser_ui/3_create/merge_request/generate_commit_message_spec.rb

+# frozen_string_literal: true
+
+module QA
+  RSpec.describe 'Create', product_group: :code_review do
+    describe 'Merge commit message' do
+      let(:project) { create(:project, :with_readme, name: 'mr-gen-commit-project') }
+
+      let(:merge_request) do
+        create(:merge_request, :no_preparation, project: project, title: 'Adding a greeting function',
+          source_branch: 'feature', target_new_branch: false)
+      end
+
+      before do
+        create(:commit,
+          project: project,
+          branch: 'feature',
+          start_branch: project.default_branch,
+          commit_message: 'foo', actions: [
+            { action: 'create', file_path: 'greeting.rb', content: "def greeting(name)\n  \"Hello, \#{name}!\"\nend\n" }
+          ])
+
+        Flow::Login.sign_in
+        merge_request.visit!
+      end
+
+      context 'when editing' do
+        it 'can be generated using GitLab Duo and merged', :external_ai_provider, only:
+          { pipeline: %i[staging staging-canary canary production] },
+          testcase: 'https://gitlab.com/gitlab-org/gitlab/-/quality/test_cases/495408' do
+          Page::MergeRequest::Show.perform do |merge_request|
+            merge_request.edit_commit_message
+            merge_request.generate_commit
+            expect(merge_request.commit_message).to include('Commit message generated by GitLab Duo')
+
+            merge_request.merge!
+            expect(merge_request).to be_merged
+          end
+        end
+      end
+    end
+  end
+end