Instruction:
Write RSpec test file for following ruby class
```ruby
# frozen_string_literal: true

module MergeRequests
  class CloseService < MergeRequests::BaseService
    include RemovesRefs

    def execute(merge_request, commit = nil)
      return merge_request unless can?(current_user, :update_merge_request, merge_request)

      # If we close MergeRequest we want to ignore validation
      # so we can close broken one (Ex. fork project removed)
      merge_request.allow_broken = true

      if merge_request.close
        expire_unapproved_key(merge_request)
        create_event(merge_request)
        merge_request_activity_counter.track_close_mr_action(user: current_user)
        create_note(merge_request)
        notification_service.async.close_mr(merge_request, current_user)
        todo_service.close_merge_request(merge_request, current_user)
        execute_hooks(merge_request, 'close')
        invalidate_cache_counts(merge_request, users: merge_request.assignees | merge_request.reviewers)
        merge_request.update_project_counter_caches
        cleanup_environments(merge_request)
        deactivate_pages_deployments(merge_request)
        abort_auto_merge(merge_request, 'merge request was closed')
        cleanup_refs(merge_request)
        trigger_merge_request_merge_status_updated(merge_request)
      end

      merge_request
    end

    private

    def create_event(merge_request)
      # Making sure MergeRequest::Metrics updates are in sync with
      # Event creation.
      Event.transaction do
        close_event = event_service.close_mr(merge_request, current_user)
        merge_request_metrics_service(merge_request).close(close_event)
      end
    end

    def expire_unapproved_key(merge_request)
      nil
    end

    def trigger_merge_request_merge_status_updated(merge_request)
      GraphqlTriggers.merge_request_merge_status_updated(merge_request)
    end
  end
end

MergeRequests::CloseService.prepend_mod

```

Response:
# frozen_string_literal: true

require 'spec_helper'

RSpec.describe MergeRequests::CloseService, feature_category: :code_review_workflow do
  let(:user) { create(:user) }
  let(:user2) { create(:user) }
  let(:guest) { create(:user) }
  let(:merge_request) { create(:merge_request, assignees: [user2], author: create(:user)) }
  let(:project) { merge_request.project }
  let!(:todo) { create(:todo, :assigned, user: user, project: project, target: merge_request, author: user2) }
  let(:service) { described_class.new(project: project, current_user: user) }

  before do
    project.add_maintainer(user)
    project.add_developer(user2)
    project.add_guest(guest)
  end

  def execute
    service.execute(merge_request)
  end

  describe '#execute' do
    it_behaves_like 'cache counters invalidator'
    it_behaves_like 'merge request reviewers cache counters invalidator'

    context 'valid params' do
      before do
        allow(service).to receive(:execute_hooks)

        perform_enqueued_jobs do
          @merge_request = execute
        end
      end

      it { expect(@merge_request).to be_valid }
      it { expect(@merge_request).to be_closed }

      it 'executes hooks with close action' do
        expect(service).to have_received(:execute_hooks)
                             .with(@merge_request, 'close')
      end

      it 'sends email to user2 about assign of new merge_request', :sidekiq_inline do
        email = ActionMailer::Base.deliveries.last
        expect(email.to.first).to eq(user2.email)
        expect(email.subject).to include(merge_request.title)
      end

      it 'creates a resource event' do
        event = @merge_request.resource_state_events.last
        expect(event.state).to eq('closed')
      end

      it 'marks todos as done' do
        expect(todo.reload).to be_done
      end

      context 'when auto merge is enabled' do
        let(:merge_request) { create(:merge_request, :merge_when_pipeline_succeeds) }

        it 'cancels the auto merge' do
          expect(@merge_request).not_to be_auto_merge_enabled
        end
      end
    end

    it 'updates metrics' do
      metrics = merge_request.metrics
      metrics_service = double(MergeRequestMetricsService)
      allow(MergeRequestMetricsService)
        .to receive(:new)
        .with(metrics)
        .and_return(metrics_service)

      expect(metrics_service).to receive(:close)

      execute
    end

    it 'calls the merge request activity counter' do
      expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
        .to receive(:track_close_mr_action)
        .with(user: user)

      execute
    end

    it 'refreshes the number of open merge requests for a valid MR', :use_clean_rails_memory_store_caching do
      expect do
        execute

        BatchLoader::Executor.clear_current
      end
        .to change { project.open_merge_requests_count }.from(1).to(0)
    end

    it 'clean up environments for the merge request' do
      expect_next_instance_of(::Environments::StopService) do |service|
        expect(service).to receive(:execute_for_merge_request_pipeline).with(merge_request)
      end

      execute
    end

    it 'schedules CleanupRefsService' do
      expect(MergeRequests::CleanupRefsService).to receive(:schedule).with(merge_request)

      execute
    end

    it 'triggers GraphQL subscription mergeRequestMergeStatusUpdated' do
      expect(GraphqlTriggers).to receive(:merge_request_merge_status_updated).with(merge_request)

      execute
    end

    context 'current user is not authorized to close merge request' do
      let(:user) { guest }

      before do
        perform_enqueued_jobs do
          @merge_request = execute
        end
      end

      it 'does not close the merge request' do
        expect(@merge_request).to be_open
      end

      it 'does not trigger GraphQL subscription mergeRequestMergeStatusUpdated' do
        expect(GraphqlTriggers).not_to receive(:merge_request_merge_status_updated)

        execute
      end
    end
  end
end


Instruction:
Write RSpec test file for following ruby class
```ruby
# frozen_string_literal: true

module MergeRequests
  class AfterCreateService < MergeRequests::BaseService
    include Gitlab::Utils::StrongMemoize

    def execute(merge_request)
      merge_request.ensure_merge_request_diff

      logger.info(**log_payload(merge_request, 'Executing hooks'))
      execute_hooks(merge_request)
      logger.info(**log_payload(merge_request, 'Executed hooks'))
      prepare_for_mergeability(merge_request)
      prepare_merge_request(merge_request)

      mark_merge_request_as_prepared(merge_request)
    end

    private

    def prepare_for_mergeability(merge_request)
      logger.info(**log_payload(merge_request, 'Creating pipeline'))
      create_pipeline_for(merge_request, current_user)
      logger.info(**log_payload(merge_request, 'Pipeline created'))
      merge_request.update_head_pipeline
      check_mergeability(merge_request)
    end

    def prepare_merge_request(merge_request)
      event_service.open_mr(merge_request, current_user)

      merge_request_activity_counter.track_create_mr_action(user: current_user, merge_request: merge_request)
      merge_request_activity_counter.track_mr_including_ci_config(user: current_user, merge_request: merge_request)

      notification_service.new_merge_request(merge_request, current_user)

      merge_request.diffs(include_stats: false).write_cache
      merge_request.create_cross_references!(current_user)

      Onboarding::ProgressService.new(merge_request.target_project.namespace).execute(action: :merge_request_created)

      todo_service.new_merge_request(merge_request, current_user)
      merge_request.cache_merge_request_closes_issues!(current_user)

      Gitlab::UsageDataCounters::MergeRequestCounter.count(:create)
      link_lfs_objects(merge_request)
    end

    def link_lfs_objects(merge_request)
      LinkLfsObjectsService.new(project: merge_request.target_project).execute(merge_request)
    end

    def check_mergeability(merge_request)
      return unless merge_request.preparing?

      # Need to set to unchecked to be able to check for mergeability or else
      # it'll be a no-op.
      merge_request.mark_as_unchecked
      merge_request.check_mergeability(async: true)
    end

    def mark_merge_request_as_prepared(merge_request)
      merge_request.update!(prepared_at: Time.current)
    end

    def logger
      @logger ||= Gitlab::AppLogger
    end

    def log_payload(merge_request, message)
      Gitlab::ApplicationContext.current.merge(
        merge_request_id: merge_request.id,
        message: message
      )
    end
  end
end

MergeRequests::AfterCreateService.prepend_mod_with('MergeRequests::AfterCreateService')

```

Response:
# frozen_string_literal: true

require 'spec_helper'

RSpec.describe MergeRequests::AfterCreateService, feature_category: :code_review_workflow do
  let_it_be(:merge_request) { create(:merge_request) }
  let(:project) { merge_request.project }

  subject(:after_create_service) do
    described_class.new(project: merge_request.target_project, current_user: merge_request.author)
  end

  describe '#execute' do
    let(:event_service) { instance_double('EventCreateService', open_mr: true) }
    let(:notification_service) { instance_double('NotificationService', new_merge_request: true) }

    before do
      allow(after_create_service).to receive(:event_service).and_return(event_service)
      allow(after_create_service).to receive(:notification_service).and_return(notification_service)
    end

    subject(:execute_service) { after_create_service.execute(merge_request) }

    it 'creates a merge request open event' do
      expect(event_service)
        .to receive(:open_mr).with(merge_request, merge_request.author)

      execute_service
    end

    it 'calls the merge request activity counter' do
      expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
        .to receive(:track_create_mr_action)
        .with(user: merge_request.author, merge_request: merge_request)

      expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
        .to receive(:track_mr_including_ci_config)
        .with(user: merge_request.author, merge_request: merge_request)

      execute_service
    end

    it 'creates a new merge request notification' do
      expect(notification_service)
        .to receive(:new_merge_request).with(merge_request, merge_request.author)

      execute_service
    end

    it 'writes diffs to the cache' do
      expect(merge_request)
        .to receive_message_chain(:diffs, :write_cache)

      execute_service
    end

    it 'creates cross references' do
      expect(merge_request)
        .to receive(:create_cross_references!).with(merge_request.author)

      execute_service
    end

    it 'creates a pipeline and updates the HEAD pipeline' do
      expect(after_create_service)
        .to receive(:create_pipeline_for).with(merge_request, merge_request.author)
      expect(merge_request).to receive(:update_head_pipeline)

      execute_service
    end

    it 'executes hooks with default action' do
      expect(project).to receive(:execute_hooks)

      execute_service
    end

    it 'calls GroupMentionWorker' do
      expect(Integrations::GroupMentionWorker).to receive(:perform_async)

      execute_service
    end

    it_behaves_like 'records an onboarding progress action', :merge_request_created do
      let(:namespace) { merge_request.target_project.namespace }
    end

    context 'when merge request is in unchecked state' do
      before do
        merge_request.mark_as_unchecked!
        execute_service
      end

      it 'does not change its state' do
        expect(merge_request.reload).to be_unchecked
      end
    end

    context 'when merge request is in preparing state' do
      before do
        merge_request.mark_as_unchecked! unless merge_request.unchecked?
        merge_request.mark_as_preparing!
      end

      it 'checks for mergeability' do
        expect(merge_request).to receive(:check_mergeability).with(async: true)

        execute_service
      end

      context 'when preparing for mergeability fails' do
        before do
          # This is only one of the possible cases that can fail. This is to
          # simulate a failure that happens during the service call.
          allow(merge_request)
            .to receive(:update_head_pipeline)
            .and_raise(StandardError)
        end

        it 'does not mark the merge request as unchecked' do
          expect { execute_service }.to raise_error(StandardError)
          expect(merge_request.reload).to be_preparing
        end
      end

      context 'when preparing merge request fails' do
        before do
          # This is only one of the possible cases that can fail. This is to
          # simulate a failure that happens during the service call.
          allow(merge_request)
            .to receive_message_chain(:diffs, :write_cache)
            .and_raise(StandardError)
        end

        it 'still checks for mergeability' do
          expect(merge_request).to receive(:check_mergeability).with(async: true)
          expect { execute_service }.to raise_error(StandardError)
        end
      end
    end

    it 'updates the prepared_at' do
      # Need to reset the `prepared_at` since it can be already set in preceding tests.
      merge_request.update!(prepared_at: nil)

      freeze_time do
        expect { execute_service }.to change { merge_request.prepared_at }
          .from(nil)
          .to(Time.current)
      end
    end

    it 'increments the usage data counter of create event' do
      counter = Gitlab::UsageDataCounters::MergeRequestCounter

      expect { execute_service }.to change { counter.read(:create) }.by(1)
    end

    context 'todos' do
      it 'does not creates todos' do
        attributes = {
          project: merge_request.target_project,
          target_id: merge_request.id,
          target_type: merge_request.class.name
        }

        expect { execute_service }.not_to change { Todo.where(attributes).count }
      end

      context 'when merge request is assigned to someone' do
        let_it_be(:assignee) { create(:user) }
        let_it_be(:merge_request) { create(:merge_request, assignees: [assignee]) }

        it 'creates a todo for new assignee' do
          attributes = {
            project: merge_request.target_project,
            author: merge_request.author,
            user: assignee,
            target_id: merge_request.id,
            target_type: merge_request.class.name,
            action: Todo::ASSIGNED,
            state: :pending
          }

          expect { execute_service }.to change { Todo.where(attributes).count }.by(1)
        end
      end

      context 'when reviewer is assigned' do
        let_it_be(:reviewer) { create(:user) }
        let_it_be(:merge_request) { create(:merge_request, reviewers: [reviewer]) }

        it 'creates a todo for new reviewer' do
          attributes = {
            project: merge_request.target_project,
            author: merge_request.author,
            user: reviewer,
            target_id: merge_request.id,
            target_type: merge_request.class.name,
            action: Todo::REVIEW_REQUESTED,
            state: :pending
          }

          expect { execute_service }.to change { Todo.where(attributes).count }.by(1)
        end
      end
    end

    context 'when saving references to issues that the created merge request closes' do
      let_it_be(:first_issue) { create(:issue, project: merge_request.target_project) }
      let_it_be(:second_issue) { create(:issue, project: merge_request.target_project) }

      it 'creates a `MergeRequestsClosingIssues` record for each issue' do
        merge_request.description = "Closes #{first_issue.to_reference} and #{second_issue.to_reference}"
        merge_request.source_branch = "feature"
        merge_request.target_branch = merge_request.target_project.default_branch
        merge_request.save!

        execute_service

        issue_ids = MergeRequestsClosingIssues.where(merge_request: merge_request).pluck(:issue_id)
        expect(issue_ids).to match_array([first_issue.id, second_issue.id])
      end
    end

    it 'tracks merge request creation in usage data' do
      expect(Gitlab::UsageDataCounters::MergeRequestCounter).to receive(:count).with(:create)

      execute_service
    end

    it 'calls MergeRequests::LinkLfsObjectsService#execute' do
      service = instance_spy(MergeRequests::LinkLfsObjectsService)
      allow(MergeRequests::LinkLfsObjectsService).to receive(:new).with(project: merge_request.target_project).and_return(service)

      execute_service

      expect(service).to have_received(:execute).with(merge_request)
    end

    describe 'logging' do
      it 'logs specific events' do
        ::Gitlab::ApplicationContext.push(caller_id: 'NewMergeRequestWorker')

        allow(Gitlab::AppLogger).to receive(:info).and_call_original

        [
          'Executing hooks',
          'Executed hooks',
          'Creating pipeline',
          'Pipeline created'
        ].each do |message|
          expect(Gitlab::AppLogger).to receive(:info).with(
            hash_including(
              'meta.caller_id' => 'NewMergeRequestWorker',
              message: message,
              merge_request_id: merge_request.id
            )
          ).and_call_original
        end

        execute_service
      end
    end
  end
end


Instruction:
Write RSpec test file for following ruby class
```ruby
# frozen_string_literal: true

module MergeRequests
  class CreatePipelineService < MergeRequests::BaseService
    def execute(merge_request)
      return cannot_create_pipeline_error unless can_create_pipeline_for?(merge_request)

      create_detached_merge_request_pipeline(merge_request)
    end

    def create_detached_merge_request_pipeline(merge_request)
      Ci::CreatePipelineService
        .new(pipeline_project(merge_request),
          current_user,
          ref: pipeline_ref_for_detached_merge_request_pipeline(merge_request),
          push_options: params[:push_options])
        .execute(:merge_request_event, merge_request: merge_request)
    end

    def can_create_pipeline_for?(merge_request)
      ##
      # UpdateMergeRequestsWorker could be retried by an exception.
      # pipelines for merge request should not be recreated in such case.
      return false if !allow_duplicate && merge_request.find_actual_head_pipeline&.merge_request?
      return false if merge_request.has_no_commits?

      true
    end

    def allow_duplicate
      params[:allow_duplicate]
    end

    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_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)
      merge_request.target_project.ci_allow_fork_pipelines_to_run_in_parent_project? &&
        can?(current_user, :create_pipeline, merge_request.target_project) &&
        can_update_source_branch_in_target_project?(merge_request)
    end

    def can_update_source_branch_in_target_project?(merge_request)
      ::Gitlab::UserAccess.new(current_user, container: merge_request.target_project)
        .can_update_branch?(merge_request.source_branch_ref)
    end

    def cannot_create_pipeline_error
      ServiceResponse.error(message: 'Cannot create a pipeline for this merge request.', payload: nil)
    end
  end
end

MergeRequests::CreatePipelineService.prepend_mod_with('MergeRequests::CreatePipelineService')

```

Response:
# frozen_string_literal: true

require 'spec_helper'

RSpec.describe MergeRequests::CreatePipelineService, :clean_gitlab_redis_cache, feature_category: :code_review_workflow do
  include ProjectForksHelper

  let_it_be(:project, refind: true) { create(:project, :repository) }
  let_it_be(:user) { create(:user) }

  let(:service) { described_class.new(project: project, current_user: actor, params: params) }
  let(:actor) { user }
  let(:params) { {} }

  before do
    project.add_developer(user)
  end

  describe '#execute' do
    subject(:response) { service.execute(merge_request) }

    before do
      stub_ci_pipeline_yaml_file(YAML.dump(config))
    end

    let(:config) do
      { rspec: { script: 'echo', only: ['merge_requests'] } }
    end

    let(:merge_request) do
      create(:merge_request,
        source_branch: 'feature',
        source_project: source_project,
        target_branch: 'master',
        target_project: project)
    end

    let(:source_project) { project }

    it 'creates a detached merge request pipeline' do
      expect { response }.to change { Ci::Pipeline.count }.by(1)

      expect(response).to be_success
      expect(response.payload).to be_persisted
      expect(response.payload).to be_detached_merge_request_pipeline
    end

    it 'defaults to merge_request_event' do
      expect(response.payload.source).to eq('merge_request_event')
    end

    context 'when push options contain ci.skip' do
      let(:params) { { push_options: { ci: { skip: true } } } }

      it 'creates a skipped pipeline' do
        expect { response }.to change { Ci::Pipeline.count }.by(1)

        expect(response).to be_success
        expect(response.payload).to be_persisted
        expect(response.payload.builds).to be_empty
        expect(response.payload).to be_skipped
      end
    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(response.payload.project).to eq(project)
        end

        context 'when the feature is disabled in CI/CD settings' do
          before do
            project.update!(ci_allow_fork_pipelines_to_run_in_parent_project: false)
          end

          it 'creates a pipeline in the source project' do
            expect(response.payload.project).to eq(source_project)
          end
        end

        context 'when source branch is protected' do
          context 'when actor does not have permission to update the protected branch in target project' do
            let!(:protected_branch) { create(:protected_branch, name: '*', project: project) }

            it 'creates a pipeline in the source project' do
              expect(response.payload.project).to eq(source_project)
            end
          end

          context 'when actor has permission to update the protected branch in target project' do
            let!(:protected_branch) { create(:protected_branch, :developers_can_merge, name: '*', project: project) }

            it 'creates a pipeline in the target project' do
              expect(response.payload.project).to eq(project)
            end
          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(response.payload.project).to eq(source_project)
        end
      end

      context 'when actor does not have permission to create pipelines' do
        let(:actor) { create(:user) }

        it 'responds with error' do
          expect(response).to be_error
          expect(response.message).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
          service.execute(merge_request)
          service.execute(merge_request)
        end.to change { Ci::Pipeline.count }.by(1)
      end

      context 'when allow_duplicate option is true' do
        let(:params) { { allow_duplicate: true } }

        it 'creates pipelines multiple times' do
          expect do
            service.execute(merge_request)
            service.execute(merge_request)
          end.to change { Ci::Pipeline.count }.by(2)
        end
      end
    end

    context 'when .gitlab-ci.yml does not use workflow:rules' do
      context 'without only: [merge_requests] keyword' do
        let(:config) do
          { rspec: { script: 'echo' } }
        end

        it 'does not create a pipeline' do
          expect { response }.not_to change { Ci::Pipeline.count }
        end
      end

      context 'with rules that specify creation on a tag' do
        let(:config) do
          {
            rspec: {
              script: 'echo',
              rules: [{ if: '$CI_COMMIT_TAG' }]
            }
          }
        end

        it 'does not create a pipeline' do
          expect { response }.not_to change { Ci::Pipeline.count }
        end
      end
    end

    context 'when workflow:rules are specified' do
      context 'when rules request creation on merge request' do
        let(:config) do
          {
            workflow: {
              rules: [{ if: '$CI_MERGE_REQUEST_ID' }]
            },
            rspec: { script: 'echo' }
          }
        end

        it 'creates a detached merge request pipeline', :aggregate_failures do
          expect { response }.to change { Ci::Pipeline.count }.by(1)

          expect(response).to be_success
          expect(response.payload).to be_persisted
          expect(response.payload).to be_detached_merge_request_pipeline
        end
      end

      context 'with rules do specify creation on a tag' do
        let(:config) do
          {
            workflow: {
              rules: [{ if: '$CI_COMMIT_TAG' }]
            },
            rspec: { script: 'echo' }
          }
        end

        it 'does not create a pipeline', :aggregate_failures do
          expect { response }.not_to change { Ci::Pipeline.count }
          expect(response).to be_error
        end
      end
    end

    context 'when merge request has no commits' do
      before do
        allow(merge_request).to receive(:has_no_commits?).and_return(true)
      end

      it 'does not create a pipeline', :aggregate_failures do
        expect { response }.not_to change { Ci::Pipeline.count }

        expect(response).to be_error
        expect(response.message).to eq('Cannot create a pipeline for this merge request.')
        expect(response.payload).to be_nil
      end
    end

    context 'when merge request pipeline creates a dynamic environment' do
      let(:config) do
        {
          review_app: {
            script: 'echo',
            only: ['merge_requests'],
            environment: { name: "review/$CI_COMMIT_REF_NAME" }
          }
        }
      end

      it 'associates merge request with the environment' do
        expect { response }.to change { Ci::Pipeline.count }.by(1)

        environment = Environment.find_by_name('review/feature')
        expect(response).to be_success
        expect(environment).to be_present
        expect(environment.merge_request).to eq(merge_request)
      end
    end
  end
end


Instruction:
Write RSpec test file for following ruby class
```ruby
# frozen_string_literal: true

module MergeRequests
  class MergeOrchestrationService < ::BaseService
    def execute(merge_request)
      return unless can_merge?(merge_request)

      merge_request.update(merge_error: nil)

      if can_merge_automatically?(merge_request)
        auto_merge_service.execute(merge_request)
      else
        merge_request.merge_async(current_user.id, params)
      end
    end

    def can_merge?(merge_request)
      can_merge_automatically?(merge_request) || can_merge_immediately?(merge_request)
    end

    def preferred_auto_merge_strategy(merge_request)
      auto_merge_service.preferred_strategy(merge_request)
    end

    private

    def can_merge_immediately?(merge_request)
      merge_request.can_be_merged_by?(current_user) &&
        merge_request.mergeable?
    end

    def can_merge_automatically?(merge_request)
      auto_merge_service.available_strategies(merge_request).any?
    end

    def auto_merge_service
      @auto_merge_service ||= AutoMergeService.new(project, current_user, params)
    end
  end
end

```

Response:
# frozen_string_literal: true

require 'spec_helper'

RSpec.describe MergeRequests::MergeOrchestrationService, feature_category: :code_review_workflow do
  let_it_be(:maintainer) { create(:user) }

  let(:merge_params) { { sha: merge_request.diff_head_sha } }
  let(:user) { maintainer }
  let(:service) { described_class.new(project, user, merge_params) }

  let!(:merge_request) do
    create(
      :merge_request,
      source_project: project, source_branch: 'feature',
      target_project: project, target_branch: 'master'
    )
  end

  shared_context 'fresh repository' do
    let_it_be(:project) { create(:project, :repository) }

    before_all do
      project.add_maintainer(maintainer)
    end
  end

  describe '#execute' do
    subject { service.execute(merge_request) }

    include_context 'fresh repository'

    context 'when merge request is mergeable' do
      context 'when merge request can be merged automatically' do
        before do
          create(:ci_pipeline, :detached_merge_request_pipeline, project: project, merge_request: merge_request)
          merge_request.update_head_pipeline

          stub_licensed_features(merge_request_approvers: true) if Gitlab.ee?
        end

        it 'schedules auto merge' do
          expect_next_instance_of(AutoMergeService, project, user, merge_params) do |service|
            expect(service).to receive(:execute).with(merge_request).and_call_original
          end

          subject

          expect(merge_request).to be_auto_merge_enabled

          if Gitlab.ee?
            expect(merge_request.auto_merge_strategy).to(
              eq(AutoMergeService::STRATEGY_MERGE_WHEN_CHECKS_PASS)
            )
          else
            expect(merge_request.auto_merge_strategy).to(
              eq(AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS)
            )
          end

          expect(merge_request).not_to be_merged
        end
      end

      context 'when merge request cannot be merged automatically' do
        it 'merges immediately', :sidekiq_inline do
          expect(merge_request)
            .to receive(:merge_async).with(user.id, merge_params)
            .and_call_original

          subject

          merge_request.reset
          expect(merge_request).to be_merged
          expect(merge_request).not_to be_auto_merge_enabled
        end
      end
    end

    context 'when merge request is not mergeable' do
      before do
        allow(merge_request).to receive(:mergeable?) { false }
      end

      it 'does nothing' do
        subject

        expect(merge_request).not_to be_auto_merge_enabled
        expect(merge_request).not_to be_merged
      end
    end
  end

  describe '#can_merge?' do
    subject { service.can_merge?(merge_request) }

    include_context 'fresh repository'

    context 'when merge request is mergeable' do
      it { is_expected.to eq(true) }
    end

    context 'when merge request is not mergeable' do
      before do
        allow(merge_request).to receive(:mergeable?) { false }
      end

      it { is_expected.to eq(false) }
    end
  end

  describe '#preferred_auto_merge_strategy' do
    subject { service.preferred_auto_merge_strategy(merge_request) }

    include_context 'fresh repository'

    context 'when merge request can be merged automatically' do
      before do
        create(:ci_pipeline, :detached_merge_request_pipeline, project: project, merge_request: merge_request)
        merge_request.update_head_pipeline

        stub_licensed_features(merge_request_approvers: true) if Gitlab.ee?
      end

      it 'fetches preferred auto merge strategy', if: Gitlab.ee? do
        is_expected.to eq(AutoMergeService::STRATEGY_MERGE_WHEN_CHECKS_PASS)
      end

      it 'fetches preferred auto merge strategy', unless: Gitlab.ee? do
        is_expected.to eq(AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS)
      end
    end

    context 'when merge request cannot be merged automatically' do
      it { is_expected.to be_nil }
    end
  end
end


Instruction:
Write RSpec test file for following ruby class
```ruby
# frozen_string_literal: true

module MergeRequests
  class UpdateService < MergeRequests::BaseService
    extend ::Gitlab::Utils::Override

    def initialize(project:, current_user: nil, params: {})
      super

      @target_branch_was_deleted = @params.delete(:target_branch_was_deleted)
    end

    def execute(merge_request)
      if Gitlab::Utils.to_boolean(params[:draft])
        merge_request.title = merge_request.draft_title
      end

      update_merge_request_with_specialized_service(merge_request) || general_fallback(merge_request)
    end

    def handle_changes(merge_request, options)
      super
      old_associations = options.fetch(:old_associations, {})
      old_labels = old_associations.fetch(:labels, [])
      old_mentioned_users = old_associations.fetch(:mentioned_users, [])
      old_assignees = old_associations.fetch(:assignees, [])
      old_reviewers = old_associations.fetch(:reviewers, [])
      old_timelogs = old_associations.fetch(:timelogs, [])
      changed_fields = merge_request.previous_changes.keys

      resolve_todos(merge_request, old_labels, old_assignees, old_reviewers)

      if merge_request.previous_changes.include?('title') ||
          merge_request.previous_changes.include?('description')
        todo_service.update_merge_request(merge_request, current_user, old_mentioned_users)
      end

      handle_target_branch_change(merge_request)
      handle_draft_status_change(merge_request, changed_fields)

      track_title_and_desc_edits(changed_fields)
      track_discussion_lock_toggle(merge_request, changed_fields)
      track_time_estimate_and_spend_edits(merge_request, old_timelogs, changed_fields)
      track_labels_change(merge_request, old_labels)

      notify_if_labels_added(merge_request, old_labels)
      notify_if_mentions_added(merge_request, old_mentioned_users)

      # Since #mark_as_unchecked triggers an update action through the MR's
      #   state machine, we want to push this as far down in the process so we
      #   avoid resetting #ActiveModel::Dirty
      #
      if merge_request.previous_changes.include?('target_branch') ||
          merge_request.previous_changes.include?('source_branch')
        merge_request.mark_as_unchecked unless merge_request.unchecked?
      end
    end

    def handle_task_changes(merge_request)
      todo_service.resolve_todos_for_target(merge_request, current_user)
      todo_service.update_merge_request(merge_request, current_user)
    end

    def reopen_service
      MergeRequests::ReopenService
    end

    def close_service
      MergeRequests::CloseService
    end

    def after_update(issuable, old_associations)
      super
      issuable.cache_merge_request_closes_issues!(current_user)
    end

    private

    attr_reader :target_branch_was_deleted

    def general_fallback(merge_request)
      # We don't allow change of source/target projects and source branch
      # after merge request was created
      params.delete(:source_project_id)
      params.delete(:target_project_id)
      params.delete(:source_branch)

      if merge_request.closed_or_merged_without_fork?
        params.delete(:target_branch)
        params.delete(:force_remove_source_branch)
      end

      update_task_event(merge_request) || update(merge_request)
    end

    def track_title_and_desc_edits(changed_fields)
      tracked_fields = %w[title description]

      return unless changed_fields.any? { |field| tracked_fields.include?(field) }

      tracked_fields.each do |action|
        next unless changed_fields.include?(action)

        merge_request_activity_counter
          .public_send("track_#{action}_edit_action".to_sym, user: current_user) # rubocop:disable GitlabSecurity/PublicSend
      end
    end

    def track_discussion_lock_toggle(merge_request, changed_fields)
      return unless changed_fields.include?('discussion_locked')

      if merge_request.discussion_locked
        merge_request_activity_counter.track_discussion_locked_action(user: current_user)
      else
        merge_request_activity_counter.track_discussion_unlocked_action(user: current_user)
      end
    end

    def track_time_estimate_and_spend_edits(merge_request, old_timelogs, changed_fields)
      merge_request_activity_counter.track_time_estimate_changed_action(user: current_user) if changed_fields.include?('time_estimate')
      merge_request_activity_counter.track_time_spent_changed_action(user: current_user) if old_timelogs != merge_request.timelogs
    end

    def track_labels_change(merge_request, old_labels)
      return if Set.new(merge_request.labels) == Set.new(old_labels)

      merge_request_activity_counter.track_labels_changed_action(user: current_user)
    end

    def notify_if_labels_added(merge_request, old_labels)
      added_labels = merge_request.labels - old_labels

      return unless added_labels.present?

      notification_service.async.relabeled_merge_request(
        merge_request,
        added_labels,
        current_user
      )
    end

    def notify_if_mentions_added(merge_request, old_mentioned_users)
      added_mentions = merge_request.mentioned_users(current_user) - old_mentioned_users

      return unless added_mentions.present?

      notification_service.async.new_mentions_in_merge_request(
        merge_request,
        added_mentions,
        current_user
      )
    end

    def resolve_todos(merge_request, old_labels, old_assignees, old_reviewers)
      return unless has_changes?(merge_request, old_labels: old_labels, old_assignees: old_assignees, old_reviewers: old_reviewers)

      resolve_todos_for(merge_request)
    end

    def handle_target_branch_change(merge_request)
      return unless merge_request.previous_changes.include?('target_branch')

      create_branch_change_note(
        merge_request,
        'target',
        target_branch_was_deleted ? 'delete' : 'update',
        merge_request.previous_changes['target_branch'].first,
        merge_request.target_branch
      )

      delete_approvals_on_target_branch_change(merge_request)
      refresh_pipelines_on_merge_requests(merge_request, allow_duplicate: true)

      abort_auto_merge(merge_request, 'target branch was changed')
    end

    def handle_draft_status_change(merge_request, changed_fields)
      return unless changed_fields.include?("title")

      old_title, new_title = merge_request.previous_changes["title"]
      old_title_draft = MergeRequest.draft?(old_title)
      new_title_draft = MergeRequest.draft?(new_title)

      if old_title_draft || new_title_draft
        # notify the draft status changed. Added/removed message is handled in the
        # email template itself, see `change_in_merge_request_draft_status_email` template.
        notify_draft_status_changed(merge_request)
        trigger_merge_request_status_updated(merge_request)
        publish_draft_change_event(merge_request) if Feature.enabled?(:additional_merge_when_checks_ready, project)
      end

      if !old_title_draft && new_title_draft
        # Marked as Draft
        merge_request_activity_counter.track_marked_as_draft_action(user: current_user)
      elsif old_title_draft && !new_title_draft
        # Unmarked as Draft
        merge_request_activity_counter.track_unmarked_as_draft_action(user: current_user)
      end
    end

    def publish_draft_change_event(merge_request)
      Gitlab::EventStore.publish(
        MergeRequests::DraftStateChangeEvent.new(
          data: { current_user_id: current_user.id, merge_request_id: merge_request.id }
        )
      )
    end

    def notify_draft_status_changed(merge_request)
      notification_service.async.change_in_merge_request_draft_status(
        merge_request,
        current_user
      )
    end

    def create_branch_change_note(issuable, branch_type, event_type, old_branch, new_branch)
      SystemNoteService.change_branch(
        issuable, issuable.project, current_user, branch_type, event_type,
        old_branch, new_branch)
    end

    override :before_update
    def before_update(merge_request, skip_spam_check: false)
      merge_request.check_for_spam(user: current_user, action: :update) unless skip_spam_check
    end

    override :handle_quick_actions
    def handle_quick_actions(merge_request)
      super

      # Ensure this parameter does not get used as an attribute
      rebase = params.delete(:rebase)

      if rebase
        rebase_from_quick_action(merge_request)
        # Ignore "/merge" if "/rebase" is used to avoid an unexpected race
        params.delete(:merge)
      end

      merge_from_quick_action(merge_request) if params[:merge]
    end

    def rebase_from_quick_action(merge_request)
      merge_request.rebase_async(current_user.id)
    end

    def merge_from_quick_action(merge_request)
      last_diff_sha = params.delete(:merge)

      ::MergeRequests::MergeOrchestrationService
        .new(project, current_user, { sha: last_diff_sha })
        .execute(merge_request)
    end

    override :quick_action_options
    def quick_action_options
      { merge_request_diff_head_sha: params.delete(:merge_request_diff_head_sha) }
    end

    def update_merge_request_with_specialized_service(merge_request)
      return unless params.delete(:use_specialized_service)

      # If we're attempting to modify only a single attribute, look up whether
      #   we have a specialized, targeted service we should use instead. We may
      #   in the future extend this to include specialized services that operate
      #   on multiple attributes, but for now limit to only single attribute
      #   updates.
      #
      return unless params.one?

      attempt_specialized_update_services(merge_request, params.each_key.first.to_sym)
    end

    def attempt_specialized_update_services(merge_request, attribute)
      case attribute
      when :assignee_ids, :assignee_id
        assignees_service.execute(merge_request)
      when :spend_time
        add_time_spent_service.execute(merge_request)
      end
    end

    def assignees_service
      @assignees_service ||= ::MergeRequests::UpdateAssigneesService
        .new(project: project, current_user: current_user, params: params)
    end

    def add_time_spent_service
      @add_time_spent_service ||= ::MergeRequests::AddSpentTimeService.new(project: project, current_user: current_user, params: params)
    end

    def new_user_ids(merge_request, user_ids, attribute)
      # prime the cache - prevent N+1 lookup during authorization loop.
      return [] if user_ids.empty?

      merge_request.project.team.max_member_access_for_user_ids(user_ids)
      User.id_in(user_ids).map do |user|
        if user.can?(:read_merge_request, merge_request)
          user.id
        else
          merge_request.errors.add(
            attribute,
            "Cannot assign #{user.to_reference} to #{merge_request.to_reference}"
          )
          nil
        end
      end.compact
    end

    def resolve_todos_for(merge_request)
      service_user = current_user

      merge_request.run_after_commit_or_now do
        ::MergeRequests::ResolveTodosService.new(merge_request, service_user).async_execute
      end
    end

    def filter_sentinel_values(param)
      param.reject { _1 == 0 }
    end

    def trigger_merge_request_status_updated(merge_request)
      GraphqlTriggers.merge_request_merge_status_updated(merge_request)
    end

    def delete_approvals_on_target_branch_change(_merge_request)
      # Overridden in EE. No-op since we only want to delete approvals in EE.
    end
  end
end

MergeRequests::UpdateService.prepend_mod_with('MergeRequests::UpdateService')

```

Response:
# frozen_string_literal: true

require 'spec_helper'

RSpec.describe MergeRequests::UpdateService, :mailer, feature_category: :code_review_workflow do
  include ProjectForksHelper

  let(:group) { create(:group, :public) }
  let(:project) { create(:project, :private, :repository, group: group) }
  let(:user) { create(:user) }
  let(:user2) { create(:user) }
  let(:user3) { create(:user) }
  let(:label) { create(:label, title: 'a', project: project) }
  let(:label2) { create(:label) }
  let(:milestone) { create(:milestone, project: project) }

  let(:merge_request) do
    create(
      :merge_request,
      :simple,
      title: 'Old title',
      description: "FYI #{user2.to_reference}",
      assignee_ids: [user3.id],
      source_project: project,
      author: create(:user)
    )
  end

  before do
    project.add_maintainer(user)
    project.add_developer(user2)
    project.add_developer(user3)
  end

  describe 'execute' do
    def find_note(starting_with)
      @merge_request.notes.find do |note|
        note && note.note.start_with?(starting_with)
      end
    end

    def find_notes(action)
      @merge_request
        .notes
        .joins(:system_note_metadata)
        .where(system_note_metadata: { action: action })
    end

    def update_merge_request(opts)
      @merge_request = MergeRequests::UpdateService.new(project: project, current_user: user, params: opts).execute(merge_request)
      @merge_request.reload
    end

    it_behaves_like 'issuable update service updating last_edited_at values' do
      let(:issuable) { merge_request }
      subject(:update_issuable) { update_merge_request(update_params) }
    end

    context 'valid params' do
      let(:locked) { true }

      let(:opts) do
        {
          title: 'New title',
          description: 'Also please fix',
          assignee_ids: [user.id],
          reviewer_ids: [],
          state_event: 'close',
          label_ids: [label.id],
          target_branch: 'target',
          force_remove_source_branch: '1',
          discussion_locked: locked
        }
      end

      let(:service) { described_class.new(project: project, current_user: current_user, params: opts) }
      let(:current_user) { user }

      before do
        allow(service).to receive(:execute_hooks)

        perform_enqueued_jobs do
          @merge_request = service.execute(merge_request)
          @merge_request.reload
        end
      end

      it 'matches base expectations' do
        expect(@merge_request).to be_valid
        expect(@merge_request.title).to eq('New title')
        expect(@merge_request.assignees).to match_array([user])
        expect(@merge_request.reviewers).to match_array([])
        expect(@merge_request).to be_closed
        expect(@merge_request.labels.count).to eq(1)
        expect(@merge_request.labels.first.title).to eq(label.name)
        expect(@merge_request.target_branch).to eq('target')
        expect(@merge_request.merge_params['force_remove_source_branch']).to eq('1')
        expect(@merge_request.discussion_locked).to be_truthy
      end

      context 'usage counters' do
        let(:merge_request2) { create(:merge_request) }
        let(:draft_merge_request) { create(:merge_request, :draft_merge_request) }

        it 'update as expected' do
          expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
            .to receive(:track_title_edit_action).once.with(user: user)
          expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
            .to receive(:track_description_edit_action).once.with(user: user)

          described_class.new(project: project, current_user: user, params: opts).execute(merge_request2)
        end

        it 'tracks Draft marking' do
          expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
            .to receive(:track_marked_as_draft_action).once.with(user: user)

          opts[:title] = "Draft: #{opts[:title]}"

          described_class.new(project: project, current_user: user, params: opts).execute(merge_request2)
        end

        it 'tracks Draft un-marking' do
          expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
            .to receive(:track_unmarked_as_draft_action).once.with(user: user)

          opts[:title] = "Non-draft/wip title string"

          described_class.new(project: project, current_user: user, params: opts).execute(draft_merge_request)
        end

        context 'when MR is locked' do
          context 'when locked again' do
            it 'does not track discussion locking' do
              expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
                .not_to receive(:track_discussion_locked_action)

              opts[:discussion_locked] = true

              described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
            end
          end

          context 'when unlocked' do
            it 'tracks dicussion unlocking' do
              expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
                .to receive(:track_discussion_unlocked_action).once.with(user: user)

              opts[:discussion_locked] = false

              described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
            end
          end
        end

        context 'when MR is unlocked' do
          let(:locked) { false }

          context 'when unlocked again' do
            it 'does not track discussion unlocking' do
              expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
                .not_to receive(:track_discussion_unlocked_action)

              opts[:discussion_locked] = false

              described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
            end
          end

          context 'when locked' do
            it 'tracks dicussion locking' do
              expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
                .to receive(:track_discussion_locked_action).once.with(user: user)

              opts[:discussion_locked] = true

              described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
            end
          end
        end

        it 'tracks time estimate and spend time changes' do
          expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
            .to receive(:track_time_estimate_changed_action).once.with(user: user)

          expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
            .to receive(:track_time_spent_changed_action).once.with(user: user)

          opts[:time_estimate] = 86400
          opts[:spend_time] = {
            duration: 3600,
            user_id: user.id,
            spent_at: Date.parse('2021-02-24')
          }

          described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
        end

        it 'tracks milestone change' do
          expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
            .to receive(:track_milestone_changed_action).once.with(user: user)

          opts[:milestone_id] = milestone.id

          described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
        end

        it 'track labels change' do
          expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
            .to receive(:track_labels_changed_action).once.with(user: user)

          opts[:label_ids] = [label2.id]

          described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
        end

        context 'reviewers' do
          context 'when reviewers changed' do
            it 'tracks reviewers changed event' do
              expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
                .to receive(:track_reviewers_changed_action).once.with(user: user)

              opts[:reviewers] = [user2]

              described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
            end
          end

          context 'when reviewers did not change' do
            it 'does not track reviewers changed event' do
              expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
                .not_to receive(:track_reviewers_changed_action)

              opts[:reviewers] = merge_request.reviewers

              described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
            end
          end
        end
      end

      context 'updating milestone' do
        context 'with milestone_id param' do
          let(:opts) { { milestone_id: milestone.id } }

          it 'sets milestone' do
            expect(@merge_request.milestone).to eq milestone
          end
        end

        context 'milestone counters cache reset' do
          let(:milestone_old) { create(:milestone, project: project) }
          let(:opts) { { milestone_id: milestone_old.id } }

          it 'deletes milestone counters' do
            expect_next_instance_of(Milestones::MergeRequestsCountService, milestone_old) do |service|
              expect(service).to receive(:delete_cache).and_call_original
            end

            expect_next_instance_of(Milestones::MergeRequestsCountService, milestone) do |service|
              expect(service).to receive(:delete_cache).and_call_original
            end

            update_merge_request(milestone_id: milestone.id)
          end

          it 'deletes milestone counters when the milestone is removed' do
            expect_next_instance_of(Milestones::MergeRequestsCountService, milestone_old) do |service|
              expect(service).to receive(:delete_cache).and_call_original
            end

            update_merge_request(milestone_id: nil)
          end

          it 'deletes milestone counters when the milestone was not set' do
            update_merge_request(milestone_id: nil)

            expect_next_instance_of(Milestones::MergeRequestsCountService, milestone) do |service|
              expect(service).to receive(:delete_cache).and_call_original
            end

            update_merge_request(milestone_id: milestone.id)
          end
        end
      end

      it 'executes hooks with update action' do
        expect(service).to have_received(:execute_hooks)
          .with(
            @merge_request,
            'update',
            old_associations: {
              labels: [],
              mentioned_users: [user2],
              assignees: [user3],
              reviewers: [],
              milestone: nil,
              total_time_spent: 0,
              time_change: 0,
              description: "FYI #{user2.to_reference}"
            }
          )
      end

      context 'with reviewers' do
        let(:opts) { { reviewer_ids: [user2.id] } }

        it 'creates system note about merge_request review request' do
          note = find_note('requested review from')

          expect(note).not_to be_nil
          expect(note.note).to include "requested review from #{user2.to_reference}"
        end

        it 'updates the tracking' do
          expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
            .to receive(:track_users_review_requested)
            .with(users: [user])

          update_merge_request(reviewer_ids: [user.id])
        end
      end

      it 'creates a resource label event' do
        event = merge_request.resource_label_events.last

        expect(event).not_to be_nil
        expect(event.label_id).to eq label.id
        expect(event.user_id).to eq user.id
      end

      it 'creates system note about title change' do
        note = find_note('changed title')

        expect(note).not_to be_nil
        expect(note.note).to eq 'changed title from **{-Old-} title** to **{+New+} title**'
      end

      it 'creates system note about description change' do
        note = find_note('changed the description')

        expect(note).not_to be_nil
        expect(note.note).to eq('changed the description')
      end

      it 'creates system note about branch change' do
        note = find_note('changed target')

        expect(note).not_to be_nil
        expect(note.note).to eq 'changed target branch from `master` to `target`'
      end

      it 'creates system note about discussion lock' do
        note = find_note('locked the discussion in this merge request')

        expect(note).not_to be_nil
        expect(note.note).to eq 'locked the discussion in this merge request'
      end

      context 'when current user cannot admin issues in the project' do
        let(:guest) { create(:user) }
        let(:current_user) { guest }

        before do
          project.add_guest(guest)
        end

        it 'filters out params that cannot be set without the :admin_merge_request permission' do
          expect(@merge_request).to be_valid
          expect(@merge_request.title).to eq('New title')
          expect(@merge_request.assignees).to match_array([user3])
          expect(@merge_request).to be_opened
          expect(@merge_request.labels.count).to eq(0)
          expect(@merge_request.target_branch).to eq('target')
          expect(@merge_request.discussion_locked).to be_falsey
          expect(@merge_request.milestone).to be_nil
        end

        context 'updating milestone' do
          RSpec.shared_examples 'does not update milestone' do
            it 'sets milestone' do
              expect(@merge_request.milestone).to be_nil
            end
          end

          context 'when milestone_id param' do
            let(:opts) { { milestone_id: milestone.id } }

            it_behaves_like 'does not update milestone'
          end

          context 'when milestone param' do
            let(:opts) { { milestone: milestone } }

            it_behaves_like 'does not update milestone'
          end
        end
      end

      context 'when not including source branch removal options' do
        before do
          opts.delete(:force_remove_source_branch)
        end

        it 'maintains the original options' do
          update_merge_request(opts)

          expect(@merge_request.merge_params["force_remove_source_branch"]).to eq("1")
        end
      end

      it_behaves_like 'reviewer_ids filter' do
        let(:opts) { {} }
        let(:execute) { update_merge_request(opts) }
      end

      context 'with an existing reviewer' do
        let(:merge_request) do
          create(:merge_request, :simple, source_project: project, reviewer_ids: [user2.id])
        end

        let(:opts) { { reviewer_ids: [IssuableFinder::Params::NONE] } }

        it 'removes reviewers' do
          expect(update_merge_request(opts).reviewers).to eq []
        end
      end

      describe 'checking for spam' do
        it 'checks for spam' do
          expect(merge_request).to receive(:check_for_spam).with(user: user, action: :update)

          update_merge_request(opts)
        end

        it 'marks the merge request invalid' do
          merge_request.spam!

          update_merge_request(title: 'New title')

          expect(merge_request).to be_invalid
        end
      end
    end

    context 'after_save callback to store_mentions' do
      let(:merge_request) { create(:merge_request, title: 'Old title', description: "simple description", source_branch: 'test', source_project: project, author: user) }
      let(:labels) { create_pair(:label, project: project) }
      let(:milestone) { create(:milestone, project: project) }
      let(:req_opts) { { source_branch: 'feature', target_branch: 'master' } }

      subject { described_class.new(project: project, current_user: user, params: opts).execute(merge_request) }

      context 'when mentionable attributes change' do
        let(:opts) { { description: "Description with #{user.to_reference}" }.merge(req_opts) }

        it 'saves mentions' do
          expect(merge_request).to receive(:store_mentions!).and_call_original

          expect { subject }.to change { MergeRequestUserMention.count }.by(1)

          expect(merge_request.referenced_users).to match_array([user])
        end
      end

      context 'when mentionable attributes do not change' do
        let(:opts) { { label_ids: [label.id, label2.id], milestone_id: milestone.id }.merge(req_opts) }

        it 'does not call store_mentions' do
          expect(merge_request).not_to receive(:store_mentions!).and_call_original

          expect { subject }.not_to change { MergeRequestUserMention.count }

          expect(merge_request.referenced_users).to be_empty
        end
      end

      context 'when save fails' do
        let(:opts) { { title: '', label_ids: labels.map(&:id), milestone_id: milestone.id } }

        it 'does not call store_mentions' do
          expect(merge_request).not_to receive(:store_mentions!).and_call_original

          expect { subject }.not_to change { MergeRequestUserMention.count }

          expect(merge_request.referenced_users).to be_empty
          expect(merge_request.valid?).to be false
        end
      end
    end

    shared_examples_for "creates a new pipeline" do
      it "creates a new pipeline" do
        expect(MergeRequests::CreatePipelineWorker)
          .to receive(:perform_async)
          .with(project.id, user.id, merge_request.id, { "allow_duplicate" => true })

        update_merge_request(target_branch: new_target_branch)
      end
    end

    shared_examples_for 'correct merge behavior' do
      let(:opts) do
        {
          merge: merge_request.diff_head_sha
        }
      end

      let(:service) { described_class.new(project: project, current_user: user, params: opts) }

      context 'without pipeline' do
        before do
          merge_request.merge_error = 'Error'

          service.execute(merge_request)
          @merge_request = MergeRequest.find(merge_request.id)
        end

        it 'merges the MR', :sidekiq_inline do
          expect(@merge_request).to be_valid
          expect(@merge_request.state).to eq('merged')
          expect(@merge_request.merge_error).to be_nil
        end
      end

      context 'with finished pipeline' do
        before do
          create(:ci_pipeline,
            project: project,
            ref: merge_request.source_branch,
            sha: merge_request.diff_head_sha,
            status: :success)

          @merge_request = service.execute(merge_request)
          @merge_request = MergeRequest.find(merge_request.id)
        end

        it 'merges the MR', :sidekiq_inline do
          expect(@merge_request).to be_valid
          expect(@merge_request.state).to eq('merged')
        end
      end

      context 'with active pipeline' do
        before do
          service_mock = double
          create(
            :ci_pipeline,
            project: project,
            ref: merge_request.source_branch,
            sha: merge_request.diff_head_sha,
            head_pipeline_of: merge_request
          )

          strategies_count = Gitlab.ee? ? :twice : :once
          expect(AutoMerge::MergeWhenPipelineSucceedsService).to receive(:new).exactly(strategies_count).with(project, user, { sha: merge_request.diff_head_sha })
            .and_return(service_mock)
          allow(service_mock).to receive(:available_for?) { true }
          expect(service_mock).to receive(:execute).with(merge_request)
        end

        it { service.execute(merge_request) }
      end

      context 'with a non-authorised user' do
        let(:visitor) { create(:user) }
        let(:service) { described_class.new(project: project, current_user: visitor, params: opts) }

        before do
          merge_request.update_attribute(:merge_error, 'Error')

          perform_enqueued_jobs do
            @merge_request = service.execute(merge_request)
            @merge_request = MergeRequest.find(merge_request.id)
          end
        end

        it 'does not merge the MR' do
          expect(@merge_request.state).to eq('opened')
          expect(@merge_request.merge_error).not_to be_nil
        end
      end

      context 'MR can not be merged when note sha != MR sha' do
        let(:opts) do
          {
            merge: 'other_commit'
          }
        end

        before do
          perform_enqueued_jobs do
            @merge_request = service.execute(merge_request)
            @merge_request = MergeRequest.find(merge_request.id)
          end
        end

        it { expect(@merge_request.state).to eq('opened') }
      end
    end

    describe 'merge' do
      it_behaves_like 'correct merge behavior'
    end

    context 'todos' do
      let!(:pending_todo) { create(:todo, :assigned, user: user, project: project, target: merge_request, author: user2) }

      context 'when the title change' do
        it 'calls MergeRequest::ResolveTodosService#async_execute' do
          expect_next_instance_of(MergeRequests::ResolveTodosService, merge_request, user) do |service|
            expect(service).to receive(:async_execute)
          end

          update_merge_request({ title: 'New title' })
        end

        it 'does not create any new todos' do
          update_merge_request({ title: 'New title' })

          expect(Todo.count).to eq(1)
        end
      end

      context 'when the description change' do
        it 'calls MergeRequest::ResolveTodosService#async_execute' do
          expect_next_instance_of(MergeRequests::ResolveTodosService, merge_request, user) do |service|
            expect(service).to receive(:async_execute)
          end

          update_merge_request({ description: "Also please fix #{user2.to_reference} #{user3.to_reference}" })
        end

        it 'creates only 1 new todo' do
          update_merge_request({ description: "Also please fix #{user2.to_reference} #{user3.to_reference}" })

          expect(Todo.count).to eq(2)
        end

        it 'triggers GraphQL description updated subscription' do
          expect(GraphqlTriggers).to receive(:issuable_description_updated).with(merge_request).and_call_original

          update_merge_request(description: 'updated description')
        end
      end

      context 'when decription is not changed' do
        it 'does not trigger GraphQL description updated subscription' do
          expect(GraphqlTriggers).not_to receive(:issuable_description_updated)

          update_merge_request(title: 'updated title')
        end
      end

      context 'when is reassigned' do
        it 'calls MergeRequest::ResolveTodosService#async_execute' do
          expect_next_instance_of(MergeRequests::ResolveTodosService, merge_request, user) do |service|
            expect(service).to receive(:async_execute)
          end

          update_merge_request({ assignee_ids: [user2.id] })
        end
      end

      context 'when reviewers gets changed' do
        it 'calls MergeRequest::ResolveTodosService#async_execute' do
          expect_next_instance_of(MergeRequests::ResolveTodosService, merge_request, user) do |service|
            expect(service).to receive(:async_execute)
          end

          update_merge_request({ reviewer_ids: [user2.id] })
        end

        it 'creates a pending todo for new review request' do
          update_merge_request({ reviewer_ids: [user2.id] })

          attributes = {
            project: project,
            author: user,
            user: user2,
            target_id: merge_request.id,
            target_type: merge_request.class.name,
            action: Todo::REVIEW_REQUESTED,
            state: :pending
          }

          expect(Todo.where(attributes).count).to eq 1
        end

        it 'sends email reviewer change notifications to old and new reviewers', :sidekiq_inline do
          merge_request.reviewers = [user2]

          perform_enqueued_jobs do
            update_merge_request({ reviewer_ids: [user3.id] })
          end

          should_email(user2)
          should_email(user3)
        end

        it 'updates open merge request counter for reviewers', :use_clean_rails_memory_store_caching do
          merge_request.reviewers = [user3]

          # Cache them to ensure the cache gets invalidated on update
          expect(user2.review_requested_open_merge_requests_count).to eq(0)
          expect(user3.review_requested_open_merge_requests_count).to eq(1)

          update_merge_request(reviewer_ids: [user2.id])

          expect(user2.review_requested_open_merge_requests_count).to eq(1)
          expect(user3.review_requested_open_merge_requests_count).to eq(0)
        end

        it_behaves_like 'triggers GraphQL subscription mergeRequestReviewersUpdated' do
          let(:action) { update_merge_request({ reviewer_ids: [user2.id] }) }
        end
      end

      context 'when reviewers did not change' do
        it_behaves_like 'does not trigger GraphQL subscription mergeRequestReviewersUpdated' do
          let(:action) { update_merge_request({ reviewer_ids: [merge_request.reviewer_ids] }) }
        end
      end

      context 'when the milestone is removed' do
        let!(:non_subscriber) { create(:user) }

        let!(:subscriber) do
          create(:user) do |u|
            merge_request.toggle_subscription(u, project)
            project.add_developer(u)
          end
        end

        it 'sends notifications for subscribers of changed milestone', :sidekiq_inline do
          merge_request.milestone = create(:milestone, project: project)

          merge_request.save!

          perform_enqueued_jobs do
            update_merge_request(milestone_id: "")
          end

          should_email(subscriber)
          should_not_email(non_subscriber)
        end
      end

      context 'when the milestone is changed' do
        let!(:non_subscriber) { create(:user) }

        let!(:subscriber) do
          create(:user) do |u|
            merge_request.toggle_subscription(u, project)
            project.add_developer(u)
          end
        end

        it 'calls MergeRequests::ResolveTodosService#async_execute' do
          expect_next_instance_of(MergeRequests::ResolveTodosService, merge_request, user) do |service|
            expect(service).to receive(:async_execute)
          end

          update_merge_request(milestone_id: create(:milestone, project: project).id)
        end

        it 'sends notifications for subscribers of changed milestone', :sidekiq_inline do
          perform_enqueued_jobs do
            update_merge_request(milestone_id: create(:milestone, project: project).id)
          end

          should_email(subscriber)
          should_not_email(non_subscriber)
        end
      end

      context 'when the labels change' do
        it 'calls MergeRequests::ResolveTodosService#async_execute' do
          expect_next_instance_of(MergeRequests::ResolveTodosService, merge_request, user) do |service|
            expect(service).to receive(:async_execute)
          end

          update_merge_request({ label_ids: [label.id] })
        end

        it 'updates updated_at' do
          travel_to(1.minute.from_now) do
            update_merge_request({ label_ids: [label.id] })
          end

          expect(merge_request.reload.updated_at).to be_future
        end
      end

      context 'when the assignee changes' do
        it 'updates open merge request counter for assignees when merge request is reassigned' do
          update_merge_request(assignee_ids: [user2.id])

          expect(user3.assigned_open_merge_requests_count).to eq 0
          expect(user2.assigned_open_merge_requests_count).to eq 1
        end

        it 'records the assignment history', :sidekiq_inline do
          original_assignee = merge_request.assignees.first!

          update_merge_request(assignee_ids: [user2.id])

          expected_events = [
            have_attributes({
              merge_request_id: merge_request.id,
              user_id: original_assignee.id,
              action: 'remove'
            }),
            have_attributes({
              merge_request_id: merge_request.id,
              user_id: user2.id,
              action: 'add'
            })
          ]

          expect(merge_request.assignment_events).to match_array(expected_events)
        end
      end

      context 'when the target branch changes' do
        it 'calls MergeRequests::ResolveTodosService#async_execute' do
          expect_next_instance_of(MergeRequests::ResolveTodosService, merge_request, user) do |service|
            expect(service).to receive(:async_execute)
          end

          update_merge_request({ target_branch: 'target' })
        end

        it "does not try to mark as unchecked if it's already unchecked" do
          allow(merge_request).to receive(:unchecked?).twice.and_return(true)
          expect(merge_request).not_to receive(:mark_as_unchecked)

          update_merge_request({ target_branch: "target" })
        end

        it_behaves_like "creates a new pipeline" do
          let(:new_target_branch) { "target" }
        end
      end

      context 'when auto merge is enabled and target branch changed' do
        before do
          AutoMergeService.new(project, user, { sha: merge_request.diff_head_sha }).execute(merge_request, AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS)
        end

        it 'calls MergeRequests::ResolveTodosService#async_execute' do
          expect_next_instance_of(MergeRequests::ResolveTodosService, merge_request, user) do |service|
            expect(service).to receive(:async_execute)
          end

          update_merge_request({ target_branch: 'target' })
        end

        it_behaves_like "creates a new pipeline" do
          let(:new_target_branch) { "target" }
        end
      end
    end

    context 'when the draft status is changed' do
      let(:title) { 'New Title' }
      let(:draft_title) { "Draft: #{title}" }
      let!(:non_subscriber) { create(:user) }
      let!(:subscriber) do
        create(:user) { |u| merge_request.toggle_subscription(u, project) }
      end

      before do
        project.add_developer(non_subscriber)
        project.add_developer(subscriber)
      end

      context 'removing draft status' do
        before do
          merge_request.update_attribute(:title, draft_title)
        end

        it 'sends notifications for subscribers', :sidekiq_inline do
          opts = { title: 'New title' }

          perform_enqueued_jobs do
            @merge_request = described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
          end

          should_email(subscriber)
          should_not_email(non_subscriber)
        end

        it 'triggers GraphQL subscription mergeRequestMergeStatusUpdated' do
          expect(GraphqlTriggers).to receive(:merge_request_merge_status_updated).with(merge_request)

          update_merge_request(title: 'New title')
        end

        context 'when additional_merge_when_checks_ready is enabled' do
          it 'publishes a DraftStateChangeEvent' do
            expected_data = {
              current_user_id: user.id,
              merge_request_id: merge_request.id
            }

            expect { update_merge_request(title: 'New title') }.to publish_event(MergeRequests::DraftStateChangeEvent).with(expected_data)
          end
        end

        context 'when additional_merge_when_checks_ready is disabled' do
          before do
            stub_feature_flags(additional_merge_when_checks_ready: false)
          end

          it 'does not publish a DraftStateChangeEvent' do
            expect { update_merge_request(title: 'New title') }.not_to publish_event(MergeRequests::DraftStateChangeEvent)
          end
        end

        context 'when removing through wip_event param' do
          it 'removes Draft from the title' do
            expect { update_merge_request({ wip_event: "ready" }) }
              .to change { merge_request.title }
              .from(draft_title)
              .to(title)
          end
        end
      end

      context 'adding draft status' do
        before do
          merge_request.update_attribute(:title, title)
        end

        it 'does not send notifications', :sidekiq_inline do
          opts = { title: 'Draft: New title' }

          perform_enqueued_jobs do
            @merge_request = described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
          end

          should_email(subscriber)
          should_not_email(non_subscriber)
        end

        context 'when additional_merge_when_checks_ready is enabled' do
          it 'publishes a DraftStateChangeEvent' do
            expected_data = {
              current_user_id: user.id,
              merge_request_id: merge_request.id
            }

            expect { update_merge_request(title: 'Draft: New title') }.to publish_event(MergeRequests::DraftStateChangeEvent).with(expected_data)
          end
        end

        context 'when additional_merge_when_checks_ready is disabled' do
          before do
            stub_feature_flags(additional_merge_when_checks_ready: false)
          end

          it 'does not publish a DraftStateChangeEvent' do
            expect { update_merge_request(title: 'Draft: New title') }.not_to publish_event(MergeRequests::DraftStateChangeEvent)
          end
        end

        it 'triggers GraphQL subscription mergeRequestMergeStatusUpdated' do
          expect(GraphqlTriggers).to receive(:merge_request_merge_status_updated).with(merge_request)

          update_merge_request(title: 'Draft: New title')
        end

        context 'when adding through wip_event param' do
          it 'adds Draft to the title' do
            expect { update_merge_request({ wip_event: "draft" }) }
              .to change { merge_request.title }
              .from(title)
              .to(draft_title)
          end
        end
      end
    end

    context 'when the merge request is relabeled' do
      let!(:non_subscriber) { create(:user) }
      let!(:subscriber) { create(:user) { |u| label.toggle_subscription(u, project) } }

      before do
        project.add_developer(non_subscriber)
        project.add_developer(subscriber)
      end

      it 'sends notifications for subscribers of newly added labels', :sidekiq_inline do
        opts = { label_ids: [label.id] }

        perform_enqueued_jobs do
          @merge_request = described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
        end

        should_email(subscriber)
        should_not_email(non_subscriber)
      end

      context 'when issue has the `label` label' do
        before do
          merge_request.labels << label
        end

        it 'does not send notifications for existing labels' do
          opts = { label_ids: [label.id, label2.id] }

          perform_enqueued_jobs do
            @merge_request = described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
          end

          should_not_email(subscriber)
          should_not_email(non_subscriber)
        end

        it 'does not send notifications for removed labels' do
          opts = { label_ids: [label2.id] }

          perform_enqueued_jobs do
            @merge_request = described_class.new(project: project, current_user: user, params: opts).execute(merge_request)
          end

          should_not_email(subscriber)
          should_not_email(non_subscriber)
        end
      end
    end

    context 'updating mentions' do
      let(:mentionable) { merge_request }

      include_examples 'updating mentions', described_class
    end

    context 'when MergeRequest has tasks' do
      before do
        update_merge_request({ description: "- [ ] Task 1\n- [ ] Task 2" })
      end

      it { expect(@merge_request.tasks?).to eq(true) }

      it_behaves_like 'updating a single task'

      context 'when tasks are marked as completed' do
        before do
          update_merge_request({ description: "- [x] Task 1\n- [X] Task 2" })
        end

        it 'creates system note about task status change' do
          note1 = find_note('marked the checklist item **Task 1** as completed')
          note2 = find_note('marked the checklist item **Task 2** as completed')

          expect(note1).not_to be_nil
          expect(note2).not_to be_nil

          description_notes = find_notes('description')
          expect(description_notes.length).to eq(1)
        end
      end

      context 'when tasks are marked as incomplete' do
        before do
          update_merge_request({ description: "- [x] Task 1\n- [X] Task 2" })
          update_merge_request({ description: "- [ ] Task 1\n- [ ] Task 2" })
        end

        it 'creates system note about task status change' do
          note1 = find_note('marked the checklist item **Task 1** as incomplete')
          note2 = find_note('marked the checklist item **Task 2** as incomplete')

          expect(note1).not_to be_nil
          expect(note2).not_to be_nil

          description_notes = find_notes('description')
          expect(description_notes.length).to eq(1)
        end
      end
    end

    context 'while saving references to issues that the updated merge request closes' do
      let(:first_issue) { create(:issue, project: project) }
      let(:second_issue) { create(:issue, project: project) }

      it 'creates a `MergeRequestsClosingIssues` record for each issue' do
        issue_closing_opts = { description: "Closes #{first_issue.to_reference} and #{second_issue.to_reference}" }
        service = described_class.new(project: project, current_user: user, params: issue_closing_opts)
        allow(service).to receive(:execute_hooks)
        service.execute(merge_request)

        issue_ids = MergeRequestsClosingIssues.where(merge_request: merge_request).pluck(:issue_id)
        expect(issue_ids).to match_array([first_issue.id, second_issue.id])
      end

      it 'removes `MergeRequestsClosingIssues` records when issues are not closed anymore' do
        create(:merge_requests_closing_issues, issue: first_issue, merge_request: merge_request)
        create(:merge_requests_closing_issues, issue: second_issue, merge_request: merge_request)

        service = described_class.new(project: project, current_user: user, params: { description: "not closing any issues" })
        allow(service).to receive(:execute_hooks)
        service.execute(merge_request.reload)

        issue_ids = MergeRequestsClosingIssues.where(merge_request: merge_request).pluck(:issue_id)
        expect(issue_ids).to be_empty
      end
    end

    context 'updating asssignee_ids' do
      context ':use_specialized_service' do
        context 'when true' do
          it 'passes the update action to ::MergeRequests::UpdateAssigneesService' do
            expect(::MergeRequests::UpdateAssigneesService)
              .to receive(:new).and_call_original

            update_merge_request({
              assignee_ids: [user2.id],
              use_specialized_service: true
            })
          end
        end

        context 'when false or nil' do
          before do
            expect(::MergeRequests::UpdateAssigneesService).not_to receive(:new)
          end

          it 'does not pass the update action to ::MergeRequests::UpdateAssigneesService when false' do
            update_merge_request({
              assignee_ids: [user2.id],
              use_specialized_service: false
            })
          end

          it 'does not pass the update action to ::MergeRequests::UpdateAssigneesService when nil' do
            update_merge_request({
              assignee_ids: [user2.id],
              use_specialized_service: nil
            })
          end
        end
      end

      it 'does not update assignee when assignee_id is invalid' do
        merge_request.update!(assignee_ids: [user.id])

        expect(MergeRequests::HandleAssigneesChangeService).not_to receive(:new)

        update_merge_request(assignee_ids: [-1])

        expect(merge_request.reload.assignees).to eq([user])
      end

      it 'unassigns assignee when user id is 0' do
        merge_request.update!(assignee_ids: [user.id])

        expect_next_instance_of(MergeRequests::HandleAssigneesChangeService, project: project, current_user: user) do |service|
          expect(service)
            .to receive(:async_execute)
            .with(merge_request, [user])
        end

        update_merge_request(assignee_ids: [0])

        expect(merge_request.assignee_ids).to be_empty
      end

      it 'saves assignee when user id is valid' do
        expect_next_instance_of(MergeRequests::HandleAssigneesChangeService, project: project, current_user: user) do |service|
          expect(service)
            .to receive(:async_execute)
            .with(merge_request, [user3])
        end

        update_merge_request(assignee_ids: [user.id])

        expect(merge_request.assignee_ids).to eq([user.id])
      end

      it 'does not update assignee_id when user cannot read issue' do
        non_member = create(:user)
        original_assignees = merge_request.assignees

        expect(MergeRequests::HandleAssigneesChangeService).not_to receive(:new)

        update_merge_request(assignee_ids: [non_member.id])

        expect(merge_request.reload.assignees).to eq(original_assignees)
      end

      context "when issuable feature is private" do
        levels = [Gitlab::VisibilityLevel::INTERNAL, Gitlab::VisibilityLevel::PUBLIC]

        levels.each do |level|
          it "does not update with unauthorized assignee when project is #{Gitlab::VisibilityLevel.level_name(level)}" do
            assignee = create(:user)
            project.update!(visibility_level: level)
            feature_visibility_attr = :"#{merge_request.model_name.plural}_access_level"
            project.project_feature.update_attribute(feature_visibility_attr, ProjectFeature::PRIVATE)

            expect { update_merge_request(assignee_ids: [assignee]) }.not_to change(merge_request.assignees, :count)
          end
        end
      end
    end

    context 'when adding time spent' do
      let(:spend_time) { { duration: 1800, user_id: user3.id } }

      context ':use_specialized_service' do
        context 'when true' do
          it 'passes the update action to ::MergeRequests::AddSpentTimeService' do
            expect(::MergeRequests::AddSpentTimeService)
              .to receive(:new).and_call_original

            update_merge_request(spend_time: spend_time, use_specialized_service: true)
          end
        end

        context 'when false or nil' do
          before do
            expect(::MergeRequests::AddSpentTimeService).not_to receive(:new)
          end

          it 'does not pass the update action to ::MergeRequests::UpdateAssigneesService when false' do
            update_merge_request(spend_time: spend_time, use_specialized_service: false)
          end

          it 'does not pass the update action to ::MergeRequests::UpdateAssigneesService when nil' do
            update_merge_request(spend_time: spend_time, use_specialized_service: nil)
          end
        end
      end
    end

    it_behaves_like 'issuable update service' do
      let(:open_issuable) { merge_request }
      let(:closed_issuable) { create(:closed_merge_request, source_project: project) }
    end

    context 'setting `allow_collaboration`' do
      let(:target_project) { create(:project, :repository, :public) }
      let(:source_project) { fork_project(target_project, nil, repository: true) }
      let(:user) { create(:user) }
      let(:merge_request) do
        create(
          :merge_request,
          source_project: source_project,
          source_branch: 'fixes',
          target_project: target_project
        )
      end

      before do
        allow(ProtectedBranch).to receive(:protected?).with(source_project, 'fixes') { false }
      end

      it 'does not allow a maintainer of the target project to set `allow_collaboration`' do
        target_project.add_developer(user)

        update_merge_request(allow_collaboration: false, title: 'Updated title')

        expect(merge_request.title).to eq('Updated title')
        expect(merge_request.allow_collaboration).to be_truthy
      end

      it 'is allowed by a user that can push to the source and can update the merge request' do
        merge_request.update!(assignees: [user])
        source_project.add_developer(user)

        update_merge_request(allow_collaboration: false, title: 'Updated title')

        expect(merge_request.title).to eq('Updated title')
        expect(merge_request.allow_collaboration).to be_falsy
      end
    end

    context 'updating `force_remove_source_branch`' do
      let(:target_project) { create(:project, :repository, :public) }
      let(:source_project) { fork_project(target_project, nil, repository: true) }
      let(:user) { target_project.first_owner }
      let(:merge_request) do
        create(
          :merge_request,
          source_project: source_project,
          source_branch: 'fixes',
          target_project: target_project
        )
      end

      it "cannot be done by members of the target project when they don't have access" do
        expect { update_merge_request(force_remove_source_branch: true) }
          .not_to change { merge_request.reload.force_remove_source_branch? }.from(nil)
      end

      it 'can be done by members of the target project if they can push to the source project' do
        source_project.add_developer(user)

        expect { update_merge_request(force_remove_source_branch: true) }
          .to change { merge_request.reload.force_remove_source_branch? }.from(nil).to(true)
      end
    end

    context 'updating `target_branch`' do
      let(:merge_request) do
        create(
          :merge_request,
          source_project: project,
          source_branch: 'mr-b',
          target_branch: 'mr-a'
        )
      end

      it 'updates to master' do
        expect(SystemNoteService).to receive(:change_branch).with(
          merge_request, project, user, 'target', 'update', 'mr-a', 'master'
        )

        expect { update_merge_request(target_branch: 'master') }
          .to change { merge_request.reload.target_branch }.from('mr-a').to('master')
      end

      it 'updates to master because of branch deletion' do
        expect(SystemNoteService).to receive(:change_branch).with(
          merge_request, project, user, 'target', 'delete', 'mr-a', 'master'
        )

        expect { update_merge_request(target_branch: 'master', target_branch_was_deleted: true) }
          .to change { merge_request.reload.target_branch }.from('mr-a').to('master')
      end

      it_behaves_like "creates a new pipeline" do
        let(:new_target_branch) { "target" }
      end
    end

    it_behaves_like 'issuable record that supports quick actions' do
      let(:existing_merge_request) { create(:merge_request, source_project: project) }
      let(:issuable) { described_class.new(project: project, current_user: user, params: params).execute(existing_merge_request) }
    end

    context 'updating labels' do
      context 'when merge request is not merged' do
        let(:label_a) { label }
        let(:label_b) { create(:label, title: 'b', project: project) }
        let(:label_c) { create(:label, title: 'c', project: project) }
        let(:label_locked) { create(:label, title: 'locked', project: project, lock_on_merge: true) }
        let(:issuable) { merge_request }

        it_behaves_like 'updating issuable labels'
        it_behaves_like 'keeps issuable labels sorted after update'
        it_behaves_like 'broadcasting issuable labels updates'
      end

      context 'when merge request has been merged' do
        let(:label_a) { create(:label, title: 'a', project: project, lock_on_merge: true) }
        let(:label_b) { create(:label, title: 'b', project: project, lock_on_merge: true) }
        let(:label_c) { create(:label, title: 'c', project: project, lock_on_merge: true) }
        let(:label_unlocked) { create(:label, title: 'unlocked', project: project) }
        let(:issuable) { merge_request }

        before do
          merge_request.update!(state: 'merged')
        end

        it_behaves_like 'updating merged MR with locked labels'

        context 'when feature flag is disabled' do
          let(:label_locked) { create(:label, title: 'locked', project: project, lock_on_merge: true) }

          before do
            stub_feature_flags(enforce_locked_labels_on_merge: false)
          end

          it_behaves_like 'updating issuable labels'
        end
      end

      def update_issuable(update_params)
        update_merge_request(update_params)
      end
    end
  end
end


Instruction:
Write RSpec test file for following ruby class
```ruby
# frozen_string_literal: true

module MergeRequests
  class MergeabilityCheckBatchService
    def initialize(merge_requests, user)
      @merge_requests = merge_requests
      @user = user
    end

    def execute
      return unless merge_requests.present?

      MergeRequests::MergeabilityCheckBatchWorker.perform_async(merge_requests.map(&:id), user&.id)
    end

    private

    attr_reader :merge_requests, :user
  end
end

```

Response:
# frozen_string_literal: true

require 'spec_helper'

RSpec.describe MergeRequests::MergeabilityCheckBatchService, feature_category: :code_review_workflow do
  describe '#execute' do
    subject { described_class.new(merge_requests, user).execute }

    let(:merge_requests) { [] }
    let_it_be(:user) { create(:user) }

    context 'when merge_requests are not empty' do
      let_it_be(:merge_request_1) { create(:merge_request) }
      let_it_be(:merge_request_2) { create(:merge_request) }
      let_it_be(:merge_requests) { [merge_request_1, merge_request_2] }

      it 'triggers batch mergeability checks' do
        expect(MergeRequests::MergeabilityCheckBatchWorker).to receive(:perform_async)
          .with([merge_request_1.id, merge_request_2.id], user.id)

        subject
      end

      context 'when user is nil' do
        let(:user) { nil }

        it 'trigger mergeability checks with nil user_id' do
          expect(MergeRequests::MergeabilityCheckBatchWorker).to receive(:perform_async)
            .with([merge_request_1.id, merge_request_2.id], nil)

          subject
        end
      end
    end

    context 'when merge_requests is empty' do
      let(:merge_requests) { MergeRequest.none }

      it 'does not trigger mergeability checks' do
        expect(MergeRequests::MergeabilityCheckBatchWorker).not_to receive(:perform_async)

        subject
      end
    end
  end
end