Allow to create pipelines for merge requests in the target project

This commit adds an extention to the pipeline creation service

app/controllers/projects/merge_requests/application_controller.rb

@@ -48,12 +48,9 @@ class Projects::MergeRequests::ApplicationController < Projects::ApplicationCont
   end
 
   def set_pipeline_variables
-    @pipelines =
-      if can?(current_user, :read_pipeline, @merge_request.source_project)
-        @merge_request.all_pipelines
-      else
-        Ci::Pipeline.none
-      end
+    @pipelines = Ci::PipelinesForMergeRequestFinder
+      .new(@merge_request, current_user)
+      .execute
   end
 
   def close_merge_request_if_no_source_project

app/controllers/projects/merge_requests/creations_controller.rb

@@ -32,13 +32,13 @@ class Projects::MergeRequests::CreationsController < Projects::MergeRequests::Ap
   end
 
   def pipelines
-    @pipelines = @merge_request.all_pipelines
+    @pipelines = Ci::PipelinesForMergeRequestFinder.new(@merge_request, current_user).execute
 
     Gitlab::PollingInterval.set_header(response, interval: 10_000)
 
     render json: {
       pipelines: PipelineSerializer
-      .new(project: @project, current_user: @current_user)
+      .new(project: @project, current_user: current_user)
       .represent(@pipelines)
     }
   end

app/finders/ci/pipelines_for_merge_request_finder.rb

@@ -7,14 +7,29 @@ module Ci
 
     EVENT = 'merge_request_event'
 
-    def initialize(merge_request)
+    def initialize(merge_request, current_user)
       @merge_request = merge_request
+      @current_user = current_user
     end
 
-    attr_reader :merge_request
+    attr_reader :merge_request, :current_user
 
-    delegate :commit_shas, :source_project, :source_branch, to: :merge_request
+    delegate :commit_shas, :target_project, :source_project, :source_branch, to: :merge_request
 
+    # Fetch all pipelines that the user can read.
+    def execute
+      if can_read_pipeline_in_target_project? && can_read_pipeline_in_source_project?
+        all
+      elsif can_read_pipeline_in_source_project?
+        all.for_project(merge_request.source_project)
+      elsif can_read_pipeline_in_target_project?
+        all.for_project(merge_request.target_project)
+      else
+        Ci::Pipeline.none
+      end
+    end
+
+    # Fetch all pipelines without permission check.
     def all
       strong_memoize(:all_pipelines) do
         next Ci::Pipeline.none unless source_project
@@ -35,13 +50,13 @@ module Ci
     def pipelines_using_cte
       cte = Gitlab::SQL::CTE.new(:shas, merge_request.all_commits.select(:sha))
 
-      source_pipelines_join = cte.table[:sha].eq(Ci::Pipeline.arel_table[:source_sha])
-      source_pipelines = filter_by(triggered_by_merge_request, cte, source_pipelines_join)
-      detached_pipelines = filter_by_sha(triggered_by_merge_request, cte)
+      source_sha_join = cte.table[:sha].eq(Ci::Pipeline.arel_table[:source_sha])
+      merged_result_pipelines = filter_by(triggered_by_merge_request, cte, source_sha_join)
+      detached_merge_request_pipelines = filter_by_sha(triggered_by_merge_request, cte)
       pipelines_for_branch = filter_by_sha(triggered_for_branch, cte)
 
       Ci::Pipeline.with(cte.to_arel) # rubocop: disable CodeReuse/ActiveRecord
-        .from_union([source_pipelines, detached_pipelines, pipelines_for_branch])
+        .from_union([merged_result_pipelines, detached_merge_request_pipelines, pipelines_for_branch])
     end
 
     def filter_by_sha(pipelines, cte)
@@ -65,8 +80,7 @@ module Ci
     # NOTE: this method returns only parent merge request pipelines.
     # Child merge request pipelines have a different source.
     def triggered_by_merge_request
-      source_project.ci_pipelines
-        .where(source: :merge_request_event, merge_request: merge_request) # rubocop: disable CodeReuse/ActiveRecord
+      Ci::Pipeline.triggered_by_merge_request(merge_request)
     end
 
     def triggered_for_branch
@@ -86,5 +100,17 @@ module Ci
 
       pipelines.order(Arel.sql(query)) # rubocop: disable CodeReuse/ActiveRecord
     end
+
+    def can_read_pipeline_in_target_project?
+      strong_memoize(:can_read_pipeline_in_target_project) do
+        Ability.allowed?(current_user, :read_pipeline, target_project)
+      end
+    end
+
+    def can_read_pipeline_in_source_project?
+      strong_memoize(:can_read_pipeline_in_source_project) do
+        Ability.allowed?(current_user, :read_pipeline, source_project)
+      end
+    end
   end
 end

app/models/ci/pipeline.rb

@@ -269,6 +269,7 @@ module Ci
     scope :for_ref, -> (ref) { where(ref: ref) }
     scope :for_id, -> (id) { where(id: id) }
     scope :for_iid, -> (iid) { where(iid: iid) }
+    scope :for_project, -> (project) { where(project: project) }
     scope :created_after, -> (time) { where('ci_pipelines.created_at > ?', time) }
     scope :created_before_id, -> (id) { where('ci_pipelines.id < ?', id) }
     scope :before_pipeline, -> (pipeline) { created_before_id(pipeline.id).outside_pipeline_family(pipeline) }
@@ -289,6 +290,15 @@ module Ci
       )
     end
 
+    # Returns the pipelines that associated with the given merge request.
+    # In general, please use `Ci::PipelinesForMergeRequestFinder` instead,
+    # for checking permission of the actor.
+    scope :triggered_by_merge_request, -> (merge_request) do
+      ci_sources.where(source: :merge_request_event,
+                       merge_request: merge_request,
+                       project: [merge_request.source_project, merge_request.target_project])
+    end
+
     # Returns the pipelines in descending order (= newest first), optionally
     # limited to a number of references.
     #

app/models/merge_request.rb

@@ -1028,6 +1028,10 @@ class MergeRequest < ApplicationRecord
     target_project != source_project
   end
 
+  def for_same_project?
+    target_project == source_project
+  end
+
   # If the merge request closes any issues, save this information in the
   # `MergeRequestsClosingIssues` model. This is a performance optimization.
   # Calculating this information for a number of merge requests requires
@@ -1293,7 +1297,7 @@ class MergeRequest < ApplicationRecord
 
   def all_pipelines
     strong_memoize(:all_pipelines) do
-      Ci::PipelinesForMergeRequestFinder.new(self).all
+      Ci::PipelinesForMergeRequestFinder.new(self, nil).all
     end
   end
 

app/services/merge_requests/base_service.rb

@@ -102,10 +102,6 @@ module MergeRequests
       MergeRequests::CreatePipelineService.new(project, user).execute(merge_request)
     end
 
-    def can_use_merge_request_ref?(merge_request)
-      !merge_request.for_fork?
-    end
-
     def abort_auto_merge(merge_request, reason)
       AutoMergeService.new(project, current_user).abort(merge_request, reason)
     end

app/services/merge_requests/create_pipeline_service.rb

@@ -9,7 +9,7 @@ module MergeRequests
     end
 
     def create_detached_merge_request_pipeline(merge_request)
-      Ci::CreatePipelineService.new(merge_request.source_project,
+      Ci::CreatePipelineService.new(pipeline_project(merge_request),
                                     current_user,
                                     ref: pipeline_ref_for_detached_merge_request_pipeline(merge_request))
         .execute(:merge_request_event, merge_request: merge_request)
@@ -31,13 +31,29 @@ module MergeRequests
 
     private
 
+    def pipeline_project(merge_request)
+      if can_create_pipeline_in_target_project?(merge_request)
+        merge_request.target_project
+      else
+        merge_request.source_project
+      end
+    end
+
     def pipeline_ref_for_detached_merge_request_pipeline(merge_request)
-      if can_use_merge_request_ref?(merge_request)
+      if can_create_pipeline_in_target_project?(merge_request)
         merge_request.ref_path
       else
         merge_request.source_branch
       end
     end
+
+    def can_create_pipeline_in_target_project?(merge_request)
+      if Gitlab::Ci::Features.allow_to_create_merge_request_pipelines_in_target_project?(merge_request.target_project)
+        can?(current_user, :create_pipeline, merge_request.target_project)
+      else
+        merge_request.for_same_project?
+      end
+    end
   end
 end
 

ee/app/services/auto_merge/add_to_merge_train_when_pipeline_succeeds_service.rb

@@ -33,7 +33,7 @@ module AutoMerge
     def available_for?(merge_request)
       super do
         merge_request.project.merge_trains_enabled? &&
-          !merge_request.for_fork? &&
+          (Gitlab::Ci::Features.allow_to_create_merge_request_pipelines_in_target_project?(merge_request.target_project) || merge_request.for_same_project?) &&
           merge_request.actual_head_pipeline&.active?
       end
     end

ee/app/services/auto_merge/merge_train_service.rb

@@ -47,7 +47,7 @@ module AutoMerge
     def available_for?(merge_request)
       super do
         merge_request.project.merge_trains_enabled? &&
-          !merge_request.for_fork? &&
+          (Gitlab::Ci::Features.allow_to_create_merge_request_pipelines_in_target_project?(merge_request.target_project) || merge_request.for_same_project?) &&
           merge_request.actual_head_pipeline&.complete?
       end
     end

ee/app/services/ee/merge_requests/create_pipeline_service.rb

@@ -7,11 +7,11 @@ module EE
 
       override :execute
       def execute(merge_request)
-        create_merge_request_pipeline_for(merge_request) || super
+        create_merged_result_pipeline_for(merge_request) || super
       end
 
-      def create_merge_request_pipeline_for(merge_request)
-        return unless can_create_merge_request_pipeline_for?(merge_request)
+      def create_merged_result_pipeline_for(merge_request)
+        return unless can_create_merged_result_pipeline_for?(merge_request)
 
         result = ::MergeRequests::MergeabilityCheckService.new(merge_request).execute(recheck: true)
 
@@ -20,7 +20,7 @@ module EE
 
           ref_payload = result.payload.fetch(:merge_ref_head)
 
-          ::Ci::CreatePipelineService.new(merge_request.source_project, current_user,
+          ::Ci::CreatePipelineService.new(merge_request.target_project, current_user,
                                           ref: merge_request.merge_ref_path,
                                           checkout_sha: ref_payload[:commit_id],
                                           target_sha: ref_payload[:target_id],
@@ -29,9 +29,9 @@ module EE
         end
       end
 
-      def can_create_merge_request_pipeline_for?(merge_request)
+      def can_create_merged_result_pipeline_for?(merge_request)
         return false unless merge_request.project.merge_pipelines_enabled?
-        return false unless can_use_merge_request_ref?(merge_request)
+        return false unless can_create_pipeline_in_target_project?(merge_request)
 
         can_create_pipeline_for?(merge_request)
       end

ee/app/services/merge_trains/create_pipeline_service.rb

@@ -16,7 +16,7 @@ module MergeTrains
     def validate(merge_request)
       return error('merge trains is disabled') unless merge_request.project.merge_trains_enabled?
       return error('merge request is not on a merge train') unless merge_request.on_train?
-      return error('fork merge request is not supported') if merge_request.for_fork?
+      return error('fork merge request is not available for this project') if !Gitlab::Ci::Features.allow_to_create_merge_request_pipelines_in_target_project?(merge_request.target_project) && merge_request.for_fork?
 
       success
     end
@@ -26,7 +26,7 @@ module MergeTrains
 
       commit_message = commit_message(merge_request, previous_ref)
 
-      ::MergeRequests::MergeToRefService.new(merge_request.project, merge_request.merge_user,
+      ::MergeRequests::MergeToRefService.new(merge_request.target_project, merge_request.merge_user,
                                              target_ref: merge_request.train_ref_path,
                                              first_parent_ref: previous_ref,
                                              commit_message: commit_message)
@@ -39,7 +39,7 @@ module MergeTrains
     end
 
     def create_pipeline(merge_request, merge_status)
-      pipeline = ::Ci::CreatePipelineService.new(merge_request.source_project, merge_request.merge_user,
+      pipeline = ::Ci::CreatePipelineService.new(merge_request.target_project, merge_request.merge_user,
         ref: merge_request.train_ref_path,
         checkout_sha: merge_status[:commit_id],
         target_sha: merge_status[:target_id],

ee/spec/services/auto_merge/add_to_merge_train_when_pipeline_succeeds_service_spec.rb

@@ -138,12 +138,15 @@ RSpec.describe AutoMerge::AddToMergeTrainWhenPipelineSucceedsService do
     end
 
     context 'when merge request is submitted from a forked project' do
+      context 'when ci_allow_to_create_merge_request_pipelines_in_target_project feature flag is disabled' do
         before do
-        allow(merge_request).to receive(:for_fork?) { true }
+          stub_feature_flags(ci_allow_to_create_merge_request_pipelines_in_target_project: false)
+          allow(merge_request).to receive(:for_same_project?) { false }
         end
 
         it { is_expected.to eq(false) }
       end
+    end
 
     context 'when the latest pipeline in the merge request is not active' do
       before do

ee/spec/services/auto_merge/merge_train_service_spec.rb

@@ -373,12 +373,15 @@ RSpec.describe AutoMerge::MergeTrainService do
     end
 
     context 'when merge request is submitted from a forked project' do
+      context 'when ci_allow_to_create_merge_request_pipelines_in_target_project feature flag is disabled' do
         before do
-        allow(merge_request).to receive(:for_fork?) { true }
+          stub_feature_flags(ci_allow_to_create_merge_request_pipelines_in_target_project: false)
+          allow(merge_request).to receive(:for_same_project?) { false }
         end
 
         it { is_expected.to be_falsy }
       end
+    end
 
     context 'when the head pipeline of the merge request has not finished' do
       before do

ee/spec/services/merge_trains/create_pipeline_service_spec.rb

@@ -57,12 +57,15 @@ RSpec.describe MergeTrains::CreatePipelineService do
     end
 
     context 'when merge request is submitted from a forked project' do
+      context 'when ci_allow_to_create_merge_request_pipelines_in_target_project feature flag is disabled' do
         before do
+          stub_feature_flags(ci_allow_to_create_merge_request_pipelines_in_target_project: false)
           allow(merge_request).to receive(:for_fork?) { true }
         end
 
         it_behaves_like 'returns an error' do
-        let(:expected_reason) { 'fork merge request is not supported' }
+          let(:expected_reason) { 'fork merge request is not available for this project' }
+        end
       end
     end
 

lib/api/merge_requests.rb

@@ -62,10 +62,8 @@ module API
       # rubocop: enable CodeReuse/ActiveRecord
 
       def merge_request_pipelines_with_access
-        authorize! :read_pipeline, user_project
-
         mr = find_merge_request_with_access(params[:merge_request_iid])
-        mr.all_pipelines
+        ::Ci::PipelinesForMergeRequestFinder.new(mr, current_user).execute
       end
 
       def automatically_mergeable?(merge_when_pipeline_succeeds, merge_request)
@@ -384,8 +382,6 @@ module API
         success Entities::Pipeline
       end
       post ':id/merge_requests/:merge_request_iid/pipelines' do
-        authorize! :create_pipeline, user_project
-
         pipeline = ::MergeRequests::CreatePipelineService
           .new(user_project, current_user, allow_duplicate: true)
           .execute(find_merge_request_with_access(params[:merge_request_iid]))

lib/gitlab/ci/features.rb

@@ -69,6 +69,10 @@ module Gitlab
       def self.bulk_insert_on_create?(project)
         ::Feature.enabled?(:ci_bulk_insert_on_create, project, default_enabled: true)
       end
+
+      def self.allow_to_create_merge_request_pipelines_in_target_project?(target_project)
+        ::Feature.enabled?(:ci_allow_to_create_merge_request_pipelines_in_target_project, target_project)
+      end
     end
   end
 end

spec/features/merge_request/user_sees_pipelines_spec.rb

@@ -84,6 +84,111 @@ RSpec.describe 'Merge request > User sees pipelines', :js do
     end
   end
 
+  describe 'fork MRs in parent project', :sidekiq_inline do
+    include ProjectForksHelper
+
+    let_it_be(:parent_project) { create(:project, :public, :repository) }
+    let_it_be(:forked_project) { fork_project(parent_project, developer_in_fork, repository: true, target_project: create(:project, :public, :repository)) }
+    let_it_be(:developer_in_parent) { create(:user) }
+    let_it_be(:developer_in_fork) { create(:user) }
+    let_it_be(:reporter_in_parent_and_developer_in_fork) { create(:user) }
+
+    let(:merge_request) do
+      create(:merge_request, :with_detached_merge_request_pipeline,
+                             source_project: forked_project, source_branch: 'feature',
+                             target_project: parent_project, target_branch: 'master')
+    end
+
+    let(:config) do
+      { test: { script: 'test', rules: [{ if: '$CI_MERGE_REQUEST_ID' }] } }
+    end
+
+    before_all do
+      parent_project.add_developer(developer_in_parent)
+      parent_project.add_reporter(reporter_in_parent_and_developer_in_fork)
+      forked_project.add_developer(developer_in_fork)
+      forked_project.add_developer(reporter_in_parent_and_developer_in_fork)
+    end
+
+    before do
+      stub_ci_pipeline_yaml_file(YAML.dump(config))
+      sign_in(actor)
+    end
+
+    after do
+      parent_project.all_pipelines.delete_all
+      forked_project.all_pipelines.delete_all
+    end
+
+    context 'when actor is a developer in parent project' do
+      let(:actor) { developer_in_parent }
+
+      it 'creates a pipeline in the parent project' do
+        visit project_merge_request_path(parent_project, merge_request)
+
+        create_merge_request_pipeline
+
+        check_pipeline(expected_project: parent_project)
+        check_head_pipeline(expected_project: parent_project)
+      end
+    end
+
+    context 'when actor is a developer in fork project' do
+      let(:actor) { developer_in_fork }
+
+      it 'creates a pipeline in the fork project' do
+        visit project_merge_request_path(parent_project, merge_request)
+
+        create_merge_request_pipeline
+
+        check_pipeline(expected_project: forked_project)
+        check_head_pipeline(expected_project: forked_project)
+      end
+    end
+
+    context 'when actor is a reporter in parent project and a developer in fork project' do
+      let(:actor) { reporter_in_parent_and_developer_in_fork }
+
+      it 'creates a pipeline in the fork project' do
+        visit project_merge_request_path(parent_project, merge_request)
+
+        create_merge_request_pipeline
+
+        check_pipeline(expected_project: forked_project)
+        check_head_pipeline(expected_project: forked_project)
+      end
+    end
+
+    def create_merge_request_pipeline
+      page.within('.merge-request-tabs') { click_link('Pipelines') }
+      click_button('Run Pipeline')
+    end
+
+    def check_pipeline(expected_project:)
+      page.within('.ci-table') do
+        expect(page).to have_selector('.commit', count: 2)
+
+        page.within(first('.commit')) do
+          page.within('.pipeline-tags') do
+            expect(page.find('.js-pipeline-url-link')[:href]).to include(expected_project.full_path)
+            expect(page).to have_content('detached')
+          end
+          page.within('.pipeline-triggerer') do
+            expect(page).to have_link(href: user_path(actor))
+          end
+        end
+      end
+    end
+
+    def check_head_pipeline(expected_project:)
+      page.within('.merge-request-tabs') { click_link('Overview') }
+
+      page.within('.ci-widget-content') do
+        expect(page.find('.pipeline-id')[:href]).to include(expected_project.full_path)
+      end
+    end
+  end
+
   describe 'race condition' do
     let(:project) { create(:project, :repository) }
     let(:user) { create(:user) }

spec/finders/ci/pipelines_for_merge_request_finder_spec.rb

@@ -3,11 +3,97 @@
 require 'spec_helper'
 
 RSpec.describe Ci::PipelinesForMergeRequestFinder do
+  describe '#execute' do
+    include ProjectForksHelper
+
+    subject { finder.execute }
+
+    let_it_be(:developer_in_parent) { create(:user) }
+    let_it_be(:developer_in_fork) { create(:user) }
+    let_it_be(:developer_in_both) { create(:user) }
+    let_it_be(:reporter_in_parent_and_developer_in_fork) { create(:user) }
+    let_it_be(:external_user) { create(:user) }
+    let_it_be(:parent_project) { create(:project, :repository, :private) }
+    let_it_be(:forked_project) { fork_project(parent_project, nil, repository: true, target_project: create(:project, :private, :repository)) }
+
+    let(:merge_request) do
+      create(:merge_request, source_project: forked_project, source_branch: 'feature',
+                             target_project: parent_project, target_branch: 'master')
+    end
+
+    let!(:pipeline_in_parent) do
+      create(:ci_pipeline, :merged_result_pipeline, merge_request: merge_request, project: parent_project)
+    end
+
+    let!(:pipeline_in_fork) do
+      create(:ci_pipeline, :merged_result_pipeline, merge_request: merge_request, project: forked_project)
+    end
+
+    let(:finder) { described_class.new(merge_request, actor) }
+
+    before_all do
+      parent_project.add_developer(developer_in_parent)
+      parent_project.add_developer(developer_in_both)
+      parent_project.add_reporter(reporter_in_parent_and_developer_in_fork)
+      forked_project.add_developer(developer_in_fork)
+      forked_project.add_developer(developer_in_both)
+      forked_project.add_developer(reporter_in_parent_and_developer_in_fork)
+    end
+
+    context 'when actor has permission to read pipelines in both parent and forked projects' do
+      let(:actor) { developer_in_both }
+
+      it 'returns all pipelines' do
+        is_expected.to eq([pipeline_in_fork, pipeline_in_parent])
+      end
+    end
+
+    context 'when actor has permission to read pipelines in both parent and forked projects' do
+      let(:actor) { reporter_in_parent_and_developer_in_fork }
+
+      it 'returns all pipelines' do
+        is_expected.to eq([pipeline_in_fork, pipeline_in_parent])
+      end
+    end
+
+    context 'when actor has permission to read pipelines in the parent project only' do
+      let(:actor) { developer_in_parent }
+
+      it 'returns pipelines in parent' do
+        is_expected.to eq([pipeline_in_parent])
+      end
+    end
+
+    context 'when actor has permission to read pipelines in the forked project only' do
+      let(:actor) { developer_in_fork }
+
+      it 'returns pipelines in fork' do
+        is_expected.to eq([pipeline_in_fork])
+      end
+    end
+
+    context 'when actor does not have permission to read pipelines' do
+      let(:actor) { external_user }
+
+      it 'returns nothing' do
+        is_expected.to be_empty
+      end
+    end
+
+    context 'when actor is nil' do
+      let(:actor) { nil }
+
+      it 'returns nothing' do
+        is_expected.to be_empty
+      end
+    end
+  end
+
   describe '#all' do
     let(:merge_request) { create(:merge_request) }
     let(:project) { merge_request.source_project }
 
-    subject { described_class.new(merge_request) }
+    subject { described_class.new(merge_request, nil) }
 
     shared_examples 'returning pipelines with proper ordering' do
       let!(:all_pipelines) do
@@ -134,7 +220,7 @@ RSpec.describe Ci::PipelinesForMergeRequestFinder do
                     branch_pipeline_2,
                     branch_pipeline])
 
-          expect(described_class.new(merge_request_2).all)
+          expect(described_class.new(merge_request_2, nil).all)
             .to eq([detached_merge_request_pipeline_2,
                     branch_pipeline_2,
                     branch_pipeline])

spec/services/merge_requests/create_pipeline_service_spec.rb

@@ -3,9 +3,12 @@
 require 'spec_helper'
 
 RSpec.describe MergeRequests::CreatePipelineService do
+  include ProjectForksHelper
+
   let_it_be(:project) { create(:project, :repository) }
   let_it_be(:user) { create(:user) }
-  let(:service) { described_class.new(project, user, params) }
+  let(:service) { described_class.new(project, actor, params) }
+  let(:actor) { user }
   let(:params) { {} }
 
   before do
@@ -26,11 +29,13 @@ RSpec.describe MergeRequests::CreatePipelineService do
     let(:merge_request) do
       create(:merge_request,
         source_branch: 'feature',
-        source_project: project,
+        source_project: source_project,
         target_branch: 'master',
         target_project: project)
     end
 
+    let(:source_project) { project }
+
     it 'creates a detached merge request pipeline' do
       expect { subject }.to change { Ci::Pipeline.count }.by(1)
 
@@ -42,6 +47,50 @@ RSpec.describe MergeRequests::CreatePipelineService do
       expect(subject.source).to eq('merge_request_event')
     end
 
+    context 'with fork merge request' do
+      let_it_be(:forked_project) { fork_project(project, nil, repository: true, target_project: create(:project, :private, :repository)) }
+      let(:source_project) { forked_project }
+
+      context 'when actor has permission to create pipelines in target project' do
+        let(:actor) { user }
+
+        it 'creates a pipeline in the target project' do
+          expect(subject.project).to eq(project)
+        end
+
+        context 'when ci_allow_to_create_merge_request_pipelines_in_target_project feature flag is disabled' do
+          before do
+            stub_feature_flags(ci_allow_to_create_merge_request_pipelines_in_target_project: false)
+          end
+
+          it 'creates a pipeline in the source project' do
+            expect(subject.project).to eq(source_project)
+          end
+        end
+      end
+
+      context 'when actor has permission to create pipelines in forked project' do
+        let(:actor) { fork_user }
+        let(:fork_user) { create(:user) }
+
+        before do
+          source_project.add_developer(fork_user)
+        end
+
+        it 'creates a pipeline in the source project' do
+          expect(subject.project).to eq(source_project)
+        end
+      end
+
+      context 'when actor does not have permission to create pipelines' do
+        let(:actor) { create(:user) }
+
+        it 'returns nothing' do
+          expect(subject.full_error_messages).to include('Insufficient permissions to create a new pipeline')
+        end
+      end
+    end
+
     context 'when service is called multiple times' do
       it 'creates a pipeline once' do
         expect do

spec/services/merge_requests/create_service_spec.rb

@@ -216,11 +216,12 @@ RSpec.describe MergeRequests::CreateService, :clean_gitlab_redis_shared_state do
               target_project.add_maintainer(user)
             end
 
-            it 'create legacy detached merge request pipeline for fork merge request' do
+            it 'create detached merge request pipeline for fork merge request' do
               merge_request.reload
 
-              expect(merge_request.actual_head_pipeline)
-                .to be_legacy_detached_merge_request_pipeline
+              head_pipeline = merge_request.actual_head_pipeline
+              expect(head_pipeline).to be_detached_merge_request_pipeline
+              expect(head_pipeline.project).to eq(target_project)
             end
           end
 

spec/services/merge_requests/refresh_service_spec.rb

@@ -225,12 +225,13 @@ RSpec.describe MergeRequests::RefreshService do
         context 'when service runs on forked project' do
           let(:project) { @fork_project }
 
-          it 'creates legacy detached merge request pipeline for fork merge request', :sidekiq_might_not_need_inline do
+          it 'creates detached merge request pipeline for fork merge request', :sidekiq_inline do
             expect { subject }
               .to change { @fork_merge_request.pipelines_for_merge_request.count }.by(1)
 
-            expect(@fork_merge_request.pipelines_for_merge_request.first)
-              .to be_legacy_detached_merge_request_pipeline
+            merge_request_pipeline = @fork_merge_request.pipelines_for_merge_request.first
+            expect(merge_request_pipeline).to be_detached_merge_request_pipeline
+            expect(merge_request_pipeline.project).to eq(@project)
           end
         end