E2E test for only/except MR rule.

qa/qa/specs/features/browser_ui/4_verify/pipeline/mr_event_rule_pipeline_spec.rb

+# frozen_string_literal: true
+
+require 'faker'
+
+module QA
+  RSpec.describe 'Verify', :runner do
+    context 'When job is configured to only run on merge_request_events' do
+      let(:mr_only_job_name) { 'mr_only_job' }
+      let(:non_mr_only_job_name) { 'non_mr_only_job' }
+      let(:executor) { "qa-runner-#{Faker::Alphanumeric.alphanumeric(8)}" }
+
+      let(:project) do
+        Resource::Project.fabricate_via_api! do |project|
+          project.name = 'merge-request-only-job'
+        end
+      end
+
+      let!(:runner) do
+        Resource::Runner.fabricate! do |runner|
+          runner.project = project
+          runner.name = executor
+          runner.tags = [executor]
+        end
+      end
+
+      let!(:ci_file) do
+        Resource::Repository::Commit.fabricate_via_api! do |commit|
+          commit.project = project
+          commit.commit_message = 'Add .gitlab-ci.yml'
+          commit.add_files(
+            [
+              {
+                file_path: '.gitlab-ci.yml',
+                content: <<~YAML
+                  #{mr_only_job_name}:
+                    script: echo 'OK'
+                    rules:
+                      - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+                  #{non_mr_only_job_name}:
+                    script: echo 'OK'
+                    rules:
+                      - if: '$CI_PIPELINE_SOURCE != "merge_request_event"'
+                YAML
+              }
+            ]
+          )
+        end
+      end
+
+      let(:merge_request) do
+        Resource::MergeRequest.fabricate_via_api! do |merge_request|
+          merge_request.project = project
+          merge_request.description = Faker::Lorem.sentence
+          merge_request.target_new_branch = false
+          merge_request.file_name = 'new.txt'
+          merge_request.file_content = Faker::Lorem.sentence
+        end
+      end
+
+      before do
+        Flow::Login.sign_in
+        merge_request.visit!
+        Page::MergeRequest::Show.perform(&:click_pipeline_link)
+      end
+
+      after do
+        runner.remove_via_api!
+        project.remove_via_api!
+      end
+
+      it 'only runs the job configured to run on merge requests', testcase: 'https://gitlab.com/gitlab-org/quality/testcases/-/issues/170' do
+        Page::Project::Pipeline::Show.perform do |pipeline|
+          aggregate_failures do
+            expect(pipeline).to have_job(mr_only_job_name)
+            expect(pipeline).to have_no_job(non_mr_only_job_name)
+          end
+        end
+      end
+    end
+  end
+end