Add latest changes from gitlab-org/gitlab@master

22 files changed, 361 insertions, 174 deletions

diff --git a/spec/controllers/groups/group_links_controller_spec.rb b/spec/controllers/groups/group_links_controller_spec.rb
index a2f7161ca41..94d3c1ffa0f 100644
--- a/spec/controllers/groups/group_links_controller_spec.rb
+++ b/spec/controllers/groups/group_links_controller_spec.rb
@@ -9,16 +9,17 @@ RSpec.describe Groups::GroupLinksController do
   let(:group_member) { create(:user) }
   let!(:project) { create(:project, group: shared_group) }
 
-  around do |example|
-    travel_to DateTime.new(2019, 4, 1) { example.run }
-  end
-
   before do
+    travel_to DateTime.new(2019, 4, 1)
     sign_in(user)
 
     shared_with_group.add_developer(group_member)
   end
 
+  after do
+    travel_back
+  end
+
   shared_examples 'placeholder is passed as `id` parameter' do |action|
     it 'returns a 404' do
       post(
diff --git a/spec/controllers/groups/group_members_controller_spec.rb b/spec/controllers/groups/group_members_controller_spec.rb
index aa9fd3759e5..19655687028 100644
--- a/spec/controllers/groups/group_members_controller_spec.rb
+++ b/spec/controllers/groups/group_members_controller_spec.rb
@@ -9,8 +9,12 @@ RSpec.describe Groups::GroupMembersController do
   let(:group) { create(:group, :public) }
   let(:membership) { create(:group_member, group: group) }
 
-  around do |example|
-    travel_to DateTime.new(2019, 4, 1) { example.run }
+  before do
+    travel_to DateTime.new(2019, 4, 1)
+  end
+
+  after do
+    travel_back
   end
 
   describe 'GET index' do
diff --git a/spec/controllers/projects/group_links_controller_spec.rb b/spec/controllers/projects/group_links_controller_spec.rb
index 2fcdfbc2436..d514c486f60 100644
--- a/spec/controllers/projects/group_links_controller_spec.rb
+++ b/spec/controllers/projects/group_links_controller_spec.rb
@@ -8,15 +8,16 @@ RSpec.describe Projects::GroupLinksController do
   let_it_be(:project) { create(:project, :private, group: group2) }
   let_it_be(:user) { create(:user) }
 
-  around do |example|
-    travel_to DateTime.new(2019, 4, 1) { example.run }
-  end
-
   before do
+    travel_to DateTime.new(2019, 4, 1)
     project.add_maintainer(user)
     sign_in(user)
   end
 
+  after do
+    travel_back
+  end
+
   describe '#create' do
     shared_context 'link project to group' do
       before do
diff --git a/spec/controllers/projects/merge_requests/drafts_controller_spec.rb b/spec/controllers/projects/merge_requests/drafts_controller_spec.rb
index af39d4dec72..580211893dc 100644
--- a/spec/controllers/projects/merge_requests/drafts_controller_spec.rb
+++ b/spec/controllers/projects/merge_requests/drafts_controller_spec.rb
@@ -297,7 +297,7 @@ RSpec.describe Projects::MergeRequests::DraftsController do
       expect { post :publish, params: params }.to change { Note.count }.by(0).and change { DraftNote.count }.by(0)
     end
 
-    it 'publishes a draft note with quick actions and applies them' do
+    it 'publishes a draft note with quick actions and applies them', :sidekiq_inline do
       project.add_developer(user2)
       create(:draft_note, merge_request: merge_request, author: user,
                           note: "/assign #{user2.to_reference}")
diff --git a/spec/controllers/projects/project_members_controller_spec.rb b/spec/controllers/projects/project_members_controller_spec.rb
index 53a7c2ca069..46a0fc8edb0 100644
--- a/spec/controllers/projects/project_members_controller_spec.rb
+++ b/spec/controllers/projects/project_members_controller_spec.rb
@@ -7,8 +7,12 @@ RSpec.describe Projects::ProjectMembersController do
   let(:group) { create(:group, :public) }
   let(:project) { create(:project, :public) }
 
-  around do |example|
-    travel_to DateTime.new(2019, 4, 1) { example.run }
+  before do
+    travel_to DateTime.new(2019, 4, 1)
+  end
+
+  after do
+    travel_back
   end
 
   describe 'GET index' do
diff --git a/spec/factories/clusters/applications/helm.rb b/spec/factories/clusters/applications/helm.rb
index db4eb961ecd..1ff1292c36e 100644
--- a/spec/factories/clusters/applications/helm.rb
+++ b/spec/factories/clusters/applications/helm.rb
@@ -4,18 +4,26 @@ FactoryBot.define do
   factory :clusters_applications_helm, class: 'Clusters::Applications::Helm' do
     cluster factory: %i(cluster provided_by_gcp)
 
-    before(:create) do
-      allow(Gitlab::Kubernetes::Helm::V2::Certificate).to receive(:generate_root)
-        .and_return(
-          double(
-            key_string: File.read(Rails.root.join('spec/fixtures/clusters/sample_key.key')),
-            cert_string: File.read(Rails.root.join('spec/fixtures/clusters/sample_cert.pem'))
+    transient do
+      helm_installed { true }
+    end
+
+    before(:create) do |_record, evaluator|
+      if evaluator.helm_installed
+        allow(Gitlab::Kubernetes::Helm::V2::Certificate).to receive(:generate_root)
+          .and_return(
+            double(
+              key_string: File.read(Rails.root.join('spec/fixtures/clusters/sample_key.key')),
+              cert_string: File.read(Rails.root.join('spec/fixtures/clusters/sample_cert.pem'))
+            )
           )
-        )
+      end
     end
 
-    after(:create) do
-      allow(Gitlab::Kubernetes::Helm::V2::Certificate).to receive(:generate_root).and_call_original
+    after(:create) do |_record, evaluator|
+      if evaluator.helm_installed
+        allow(Gitlab::Kubernetes::Helm::V2::Certificate).to receive(:generate_root).and_call_original
+      end
     end
 
     trait :not_installable do
@@ -78,14 +86,19 @@ FactoryBot.define do
       updated_at { ClusterWaitForAppInstallationWorker::TIMEOUT.ago }
     end
 
+    # Common trait used by the apps below
+    trait :no_helm_installed do
+      cluster factory: %i(cluster provided_by_gcp)
+
+      transient do
+        helm_installed { false }
+      end
+    end
+
     factory :clusters_applications_ingress, class: 'Clusters::Applications::Ingress' do
       modsecurity_enabled { false }
       cluster factory: %i(cluster with_installed_helm provided_by_gcp)
 
-      trait :no_helm_installed do
-        cluster factory: %i(cluster provided_by_gcp)
-      end
-
       trait :modsecurity_blocking do
         modsecurity_enabled { true }
         modsecurity_mode { :blocking }
@@ -108,62 +121,34 @@ FactoryBot.define do
     factory :clusters_applications_cert_manager, class: 'Clusters::Applications::CertManager' do
       email { 'admin@example.com' }
       cluster factory: %i(cluster with_installed_helm provided_by_gcp)
-
-      trait :no_helm_installed do
-        cluster factory: %i(cluster provided_by_gcp)
-      end
     end
 
     factory :clusters_applications_elastic_stack, class: 'Clusters::Applications::ElasticStack' do
       cluster factory: %i(cluster with_installed_helm provided_by_gcp)
-
-      trait :no_helm_installed do
-        cluster factory: %i(cluster provided_by_gcp)
-      end
     end
 
     factory :clusters_applications_crossplane, class: 'Clusters::Applications::Crossplane' do
       stack { 'gcp' }
       cluster factory: %i(cluster with_installed_helm provided_by_gcp)
-
-      trait :no_helm_installed do
-        cluster factory: %i(cluster provided_by_gcp)
-      end
     end
 
     factory :clusters_applications_prometheus, class: 'Clusters::Applications::Prometheus' do
       cluster factory: %i(cluster with_installed_helm provided_by_gcp)
-
-      trait :no_helm_installed do
-        cluster factory: %i(cluster provided_by_gcp)
-      end
     end
 
     factory :clusters_applications_runner, class: 'Clusters::Applications::Runner' do
       runner factory: %i(ci_runner)
       cluster factory: %i(cluster with_installed_helm provided_by_gcp)
-
-      trait :no_helm_installed do
-        cluster factory: %i(cluster provided_by_gcp)
-      end
     end
 
     factory :clusters_applications_knative, class: 'Clusters::Applications::Knative' do
       hostname { 'example.com' }
       cluster factory: %i(cluster with_installed_helm provided_by_gcp)
-
-      trait :no_helm_installed do
-        cluster factory: %i(cluster provided_by_gcp)
-      end
     end
 
     factory :clusters_applications_jupyter, class: 'Clusters::Applications::Jupyter' do
       oauth_application factory: :oauth_application
       cluster factory: %i(cluster with_installed_helm provided_by_gcp project)
-
-      trait :no_helm_installed do
-        cluster factory: %i(cluster provided_by_gcp)
-      end
     end
 
     factory :clusters_applications_fluentd, class: 'Clusters::Applications::Fluentd' do
@@ -171,18 +156,10 @@ FactoryBot.define do
       waf_log_enabled { true }
       cilium_log_enabled { true }
       cluster factory: %i(cluster with_installed_helm provided_by_gcp)
-
-      trait :no_helm_installed do
-        cluster factory: %i(cluster provided_by_gcp)
-      end
     end
 
     factory :clusters_applications_cilium, class: 'Clusters::Applications::Cilium' do
       cluster factory: %i(cluster with_installed_helm provided_by_gcp)
-
-      trait :no_helm_installed do
-        cluster factory: %i(cluster provided_by_gcp)
-      end
     end
   end
 end
diff --git a/spec/features/error_pages_spec.rb b/spec/features/error_pages_spec.rb
index 77f8aa87237..8dc9e5ade46 100644
--- a/spec/features/error_pages_spec.rb
+++ b/spec/features/error_pages_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-RSpec.describe 'Error Pages' do
+RSpec.describe 'Error Pages', :js do
   let(:user) { create(:user) }
   let(:project) { create(:project, :public) }
 
@@ -14,7 +14,12 @@ RSpec.describe 'Error Pages' do
     it 'shows nav links' do
       expect(page).to have_link("Home", href: root_path)
       expect(page).to have_link("Help", href: help_path)
-      expect(page).to have_link(nil, href: destroy_user_session_path)
+    end
+
+    it 'allows user to sign out' do
+      click_link 'Sign out and sign in with a different account'
+
+      expect(page).to have_current_path(new_user_session_path)
     end
   end
 
diff --git a/spec/features/projects/user_sees_user_popover_spec.rb b/spec/features/projects/user_sees_user_popover_spec.rb
index 52e65deae3b..e357824a533 100644
--- a/spec/features/projects/user_sees_user_popover_spec.rb
+++ b/spec/features/projects/user_sees_user_popover_spec.rb
@@ -35,7 +35,7 @@ RSpec.describe 'User sees user popover', :js do
       end
     end
 
-    it "displays user popover in system note" do
+    it 'displays user popover in system note', :sidekiq_inline do
       add_note("/assign @#{user.username}")
 
       find('.system-note-message .js-user-link').hover
diff --git a/spec/frontend/content_editor/markdown_processing_spec.js b/spec/frontend/content_editor/markdown_processing_spec.js
index 79ddfb8b125..e435af30e9f 100644
--- a/spec/frontend/content_editor/markdown_processing_spec.js
+++ b/spec/frontend/content_editor/markdown_processing_spec.js
@@ -1,13 +1,12 @@
-import createEditor from '~/content_editor/services/create_editor';
-import toMarkdown from '~/content_editor/services/to_markdown';
+import { createEditor } from '~/content_editor';
 import { loadMarkdownApiExamples, loadMarkdownApiResult } from './markdown_processing_examples';
 
 describe('markdown processing', () => {
   // Ensure we generate same markdown that was provided to Markdown API.
   it.each(loadMarkdownApiExamples())('correctly handles %s', async (testName, markdown) => {
     const { html } = loadMarkdownApiResult(testName);
-    const editor = await createEditor({ content: html });
+    const editor = await createEditor({ content: markdown, renderMarkdown: () => html });
 
-    expect(toMarkdown(editor.state.doc)).toBe(markdown);
+    expect(editor.getSerializedContent()).toBe(markdown);
   });
 });
diff --git a/spec/frontend/content_editor/services/create_editor_spec.js b/spec/frontend/content_editor/services/create_editor_spec.js
new file mode 100644
index 00000000000..4cf63e608eb
--- /dev/null
+++ b/spec/frontend/content_editor/services/create_editor_spec.js
@@ -0,0 +1,39 @@
+import { PROVIDE_SERIALIZER_OR_RENDERER_ERROR } from '~/content_editor/constants';
+import createEditor from '~/content_editor/services/create_editor';
+import createMarkdownSerializer from '~/content_editor/services/markdown_serializer';
+
+jest.mock('~/content_editor/services/markdown_serializer');
+
+describe('content_editor/services/create_editor', () => {
+  const buildMockSerializer = () => ({
+    serialize: jest.fn(),
+    deserialize: jest.fn(),
+  });
+
+  describe('creating an editor', () => {
+    it('uses markdown serializer when a renderMarkdown function is provided', async () => {
+      const renderMarkdown = () => true;
+      const mockSerializer = buildMockSerializer();
+      createMarkdownSerializer.mockReturnValueOnce(mockSerializer);
+
+      await createEditor({ renderMarkdown });
+
+      expect(createMarkdownSerializer).toHaveBeenCalledWith({ render: renderMarkdown });
+    });
+
+    it('uses custom serializer when it is provided', async () => {
+      const mockSerializer = buildMockSerializer();
+      const serializedContent = '**bold**';
+
+      mockSerializer.serialize.mockReturnValueOnce(serializedContent);
+
+      const editor = await createEditor({ serializer: mockSerializer });
+
+      expect(editor.getSerializedContent()).toBe(serializedContent);
+    });
+
+    it('throws an error when neither a serializer or renderMarkdown fn are provided', async () => {
+      await expect(createEditor()).rejects.toThrow(PROVIDE_SERIALIZER_OR_RENDERER_ERROR);
+    });
+  });
+});
diff --git a/spec/graphql/resolvers/repository_branch_names_resolver_spec.rb b/spec/graphql/resolvers/repository_branch_names_resolver_spec.rb
new file mode 100644
index 00000000000..398dd7a2e2e
--- /dev/null
+++ b/spec/graphql/resolvers/repository_branch_names_resolver_spec.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Resolvers::RepositoryBranchNamesResolver do
+  include GraphqlHelpers
+
+  let(:project) { create(:project, :repository) }
+
+  describe '#resolve' do
+    subject(:resolve_branch_names) do
+      resolve(
+        described_class,
+        obj: project.repository,
+        args: { search_pattern: pattern },
+        ctx: { current_user: project.creator }
+      )
+    end
+
+    context 'with empty search pattern' do
+      let(:pattern) { '' }
+
+      it 'returns nil' do
+        expect(resolve_branch_names).to eq(nil)
+      end
+    end
+
+    context 'with a valid search pattern' do
+      let(:pattern) { 'mas*' }
+
+      it 'returns matching branches' do
+        expect(resolve_branch_names).to match_array(['master'])
+      end
+    end
+  end
+end
diff --git a/spec/graphql/types/repository_type_spec.rb b/spec/graphql/types/repository_type_spec.rb
index a3bb7e502f2..fa1e54dfcfa 100644
--- a/spec/graphql/types/repository_type_spec.rb
+++ b/spec/graphql/types/repository_type_spec.rb
@@ -14,4 +14,6 @@ RSpec.describe GitlabSchema.types['Repository'] do
   specify { expect(described_class).to have_graphql_field(:exists, calls_gitaly?: true, complexity: 2) }
 
   specify { expect(described_class).to have_graphql_field(:blobs) }
+
+  specify { expect(described_class).to have_graphql_field(:branch_names, calls_gitaly?: true, complexity: 170) }
 end
diff --git a/spec/lib/gitlab/ci/pipeline/chain/pipeline/process_spec.rb b/spec/lib/gitlab/ci/pipeline/chain/pipeline/process_spec.rb
index 0fc46211044..3885cea2d1b 100644
--- a/spec/lib/gitlab/ci/pipeline/chain/pipeline/process_spec.rb
+++ b/spec/lib/gitlab/ci/pipeline/chain/pipeline/process_spec.rb
@@ -23,21 +23,6 @@ RSpec.describe Gitlab::Ci::Pipeline::Chain::Pipeline::Process do
 
       perform
     end
-
-    context 'with async processing disabled' do
-      before do
-        stub_feature_flags(ci_async_initial_pipeline_processing: false)
-      end
-
-      it 'processes pipeline inline' do
-        expect(::Ci::ProcessPipelineService)
-          .to receive(:new)
-          .with(pipeline)
-          .and_call_original
-
-        perform
-      end
-    end
   end
 
   describe '#break?' do
diff --git a/spec/migrations/move_container_registry_enabled_to_project_features_spec.rb b/spec/migrations/move_container_registry_enabled_to_project_features2_spec.rb
index c7b07f3ef37..11d43a36bc9 100644
--- a/spec/migrations/move_container_registry_enabled_to_project_features_spec.rb
+++ b/spec/migrations/move_container_registry_enabled_to_project_features2_spec.rb
@@ -1,9 +1,9 @@
 # frozen_string_literal: true
 
 require 'spec_helper'
-require Rails.root.join('db', 'post_migrate', '20210226120851_move_container_registry_enabled_to_project_features.rb')
+require Rails.root.join('db', 'post_migrate', '20210401131948_move_container_registry_enabled_to_project_features2.rb')
 
-RSpec.describe MoveContainerRegistryEnabledToProjectFeatures, :migration do
+RSpec.describe MoveContainerRegistryEnabledToProjectFeatures2, :migration do
   let(:namespace) { table(:namespaces).create!(name: 'gitlab', path: 'gitlab-org') }
 
   let!(:projects) do
@@ -30,6 +30,10 @@ RSpec.describe MoveContainerRegistryEnabledToProjectFeatures, :migration do
   it 'schedules jobs for ranges of projects' do
     migrate!
 
+    # Since track_jobs is true, each job should have an entry in the background_migration_jobs
+    # table.
+    expect(table(:background_migration_jobs).count).to eq(2)
+
     expect(described_class::MIGRATION)
       .to be_scheduled_delayed_migration(2.minutes, projects[0].id, projects[2].id)
 
diff --git a/spec/requests/api/notes_spec.rb b/spec/requests/api/notes_spec.rb
index baab72d106f..d4f8b841c96 100644
--- a/spec/requests/api/notes_spec.rb
+++ b/spec/requests/api/notes_spec.rb
@@ -251,7 +251,7 @@ RSpec.describe API::Notes do
         expect { subject }.not_to change { Note.where(system: false).count }
       end
 
-      it 'does however create a system note about the change' do
+      it 'does however create a system note about the change', :sidekiq_inline do
         expect { subject }.to change { Note.system.count }.by(1)
       end
 
diff --git a/spec/serializers/diff_file_entity_spec.rb b/spec/serializers/diff_file_entity_spec.rb
index 1b8456e5c49..b8c5ccb9e7b 100644
--- a/spec/serializers/diff_file_entity_spec.rb
+++ b/spec/serializers/diff_file_entity_spec.rb
@@ -49,6 +49,14 @@ RSpec.describe DiffFileEntity do
 
       expect(subject).to include(:load_collapsed_diff_url)
     end
+
+    context 'when diff_view is unknown' do
+      let(:options) { { diff_view: :unknown } }
+
+      it 'hides highlighted_diff_lines and parallel_diff_lines' do
+        is_expected.not_to include(:highlighted_diff_lines, :parallel_diff_lines)
+      end
+    end
   end
 
   describe '#parallel_diff_lines' do
diff --git a/spec/services/draft_notes/publish_service_spec.rb b/spec/services/draft_notes/publish_service_spec.rb
index f83e91b683f..f93622dc25a 100644
--- a/spec/services/draft_notes/publish_service_spec.rb
+++ b/spec/services/draft_notes/publish_service_spec.rb
@@ -229,7 +229,7 @@ RSpec.describe DraftNotes::PublishService do
     expect(DraftNote.count).to eq(2)
   end
 
-  context 'with quick actions' do
+  context 'with quick actions', :sidekiq_inline do
     it 'performs quick actions' do
       other_user = create(:user)
       project.add_developer(other_user)
diff --git a/spec/services/merge_requests/handle_assignees_change_service_spec.rb b/spec/services/merge_requests/handle_assignees_change_service_spec.rb
new file mode 100644
index 00000000000..cc595aab04b
--- /dev/null
+++ b/spec/services/merge_requests/handle_assignees_change_service_spec.rb
@@ -0,0 +1,114 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe MergeRequests::HandleAssigneesChangeService do
+  let_it_be(:project) { create(:project, :repository) }
+  let_it_be(:user) { create(:user) }
+  let_it_be(:assignee) { create(:user) }
+  let_it_be(:merge_request) { create(:merge_request, author: user, source_project: project, assignees: [assignee]) }
+  let_it_be(:old_assignees) { create_list(:user, 3) }
+
+  let(:options) { {} }
+  let(:service) { described_class.new(project, user) }
+
+  before_all do
+    project.add_maintainer(user)
+    project.add_developer(assignee)
+
+    old_assignees.each do |old_assignee|
+      project.add_developer(old_assignee)
+    end
+  end
+
+  describe '#async_execute' do
+    def async_execute
+      service.async_execute(merge_request, old_assignees, options)
+    end
+
+    it 'performs MergeRequests::HandleAssigneesChangeWorker asynchronously' do
+      expect(MergeRequests::HandleAssigneesChangeWorker)
+        .to receive(:perform_async)
+        .with(
+          merge_request.id,
+          user.id,
+          old_assignees.map(&:id),
+          options
+        )
+
+      async_execute
+    end
+
+    context 'when async_handle_merge_request_assignees_change feature is disabled' do
+      before do
+        stub_feature_flags(async_handle_merge_request_assignees_change: false)
+      end
+
+      it 'calls #execute' do
+        expect(service).to receive(:execute).with(merge_request, old_assignees, options)
+
+        async_execute
+      end
+    end
+  end
+
+  describe '#execute' do
+    def execute
+      service.execute(merge_request, old_assignees, options)
+    end
+
+    it 'creates assignee note' do
+      execute
+
+      note = merge_request.notes.last
+
+      expect(note).not_to be_nil
+      expect(note.note).to include "assigned to #{assignee.to_reference} and unassigned #{old_assignees.map(&:to_reference).to_sentence}"
+    end
+
+    it 'sends email notifications to old and new assignees', :mailer, :sidekiq_inline do
+      perform_enqueued_jobs do
+        execute
+      end
+
+      should_email(assignee)
+      old_assignees.each do |old_assignee|
+        should_email(old_assignee)
+      end
+    end
+
+    it 'creates pending todo for assignee' do
+      execute
+
+      todo = assignee.todos.last
+
+      expect(todo).to be_pending
+    end
+
+    it 'tracks users assigned event' do
+      expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
+        .to receive(:track_users_assigned_to_mr).once.with(users: [assignee])
+
+      execute
+    end
+
+    it 'tracks assignees changed event' do
+      expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
+        .to receive(:track_assignees_changed_action).once.with(user: user)
+
+      execute
+    end
+
+    context 'when execute_hooks option is set to true' do
+      let(:options) { { execute_hooks: true } }
+
+      it 'execute hooks and services' do
+        expect(merge_request.project).to receive(:execute_hooks).with(anything, :merge_request_hooks)
+        expect(merge_request.project).to receive(:execute_services).with(anything, :merge_request_hooks)
+        expect(service).to receive(:enqueue_jira_connect_messages_for).with(merge_request)
+
+        execute
+      end
+    end
+  end
+end
diff --git a/spec/services/merge_requests/update_assignees_service_spec.rb b/spec/services/merge_requests/update_assignees_service_spec.rb
index aa6aad854a6..de03aab5418 100644
--- a/spec/services/merge_requests/update_assignees_service_spec.rb
+++ b/spec/services/merge_requests/update_assignees_service_spec.rb
@@ -37,9 +37,11 @@ RSpec.describe MergeRequests::UpdateAssigneesService do
 
     context 'when the parameters are valid' do
       it 'updates the MR, and queues the more expensive work for later' do
-        expect(MergeRequests::AssigneesChangeWorker)
-          .to receive(:perform_async)
-          .with(merge_request.id, user.id, [user3.id])
+        expect_next(MergeRequests::HandleAssigneesChangeService, project, user) do |service|
+          expect(service)
+            .to receive(:async_execute)
+            .with(merge_request, [user3], execute_hooks: true)
+        end
 
         expect { update_merge_request }
           .to change(merge_request, :assignees).to([user2])
@@ -54,9 +56,11 @@ RSpec.describe MergeRequests::UpdateAssigneesService do
       end
 
       it 'is more efficient than using the full update-service' do
-        allow(MergeRequests::AssigneesChangeWorker)
-          .to receive(:perform_async)
-          .with(merge_request.id, user.id, [user3.id])
+        allow_next(MergeRequests::HandleAssigneesChangeService, project, user) do |service|
+          expect(service)
+            .to receive(:async_execute)
+            .with(merge_request, [user3], execute_hooks: true)
+        end
 
         other_mr = create(:merge_request, :simple, :unique_branches,
                           title: merge_request.title,
@@ -72,17 +76,4 @@ RSpec.describe MergeRequests::UpdateAssigneesService do
       end
     end
   end
-
-  describe '#handle_assignee_changes' do
-    subject { service.handle_assignee_changes(merge_request, [user2]) }
-
-    it 'calls UpdateService#handle_assignee_changes and executes hooks' do
-      expect(service).to receive(:handle_assignees_change).with(merge_request, [user2])
-      expect(merge_request.project).to receive(:execute_hooks).with(anything, :merge_request_hooks)
-      expect(merge_request.project).to receive(:execute_services).with(anything, :merge_request_hooks)
-      expect(service).to receive(:enqueue_jira_connect_messages_for).with(merge_request)
-
-      subject
-    end
-  end
 end
diff --git a/spec/services/merge_requests/update_service_spec.rb b/spec/services/merge_requests/update_service_spec.rb
index 579d274d910..24b7c3b933b 100644
--- a/spec/services/merge_requests/update_service_spec.rb
+++ b/spec/services/merge_requests/update_service_spec.rb
@@ -205,30 +205,6 @@ RSpec.describe MergeRequests::UpdateService, :mailer do
           MergeRequests::UpdateService.new(project, user, opts).execute(merge_request)
         end
 
-        context 'assignees' do
-          context 'when assignees changed' do
-            it 'tracks assignees changed event' do
-              expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
-                .to receive(:track_assignees_changed_action).once.with(user: user)
-
-              opts[:assignees] = [user2]
-
-              MergeRequests::UpdateService.new(project, user, opts).execute(merge_request)
-            end
-          end
-
-          context 'when assignees did not change' do
-            it 'does not track assignees changed event' do
-              expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
-                .not_to receive(:track_assignees_changed_action)
-
-              opts[:assignees] = merge_request.assignees
-
-              MergeRequests::UpdateService.new(project, user, opts).execute(merge_request)
-            end
-          end
-        end
-
         context 'reviewers' do
           context 'when reviewers changed' do
             it 'tracks reviewers changed event' do
@@ -326,21 +302,6 @@ RSpec.describe MergeRequests::UpdateService, :mailer do
           )
       end
 
-      it 'sends email to user2 about assign of new merge request and email to user3 about merge request unassignment', :sidekiq_might_not_need_inline do
-        deliveries = ActionMailer::Base.deliveries
-        email = deliveries.last
-        recipients = deliveries.last(2).flat_map(&:to)
-        expect(recipients).to include(user2.email, user3.email)
-        expect(email.subject).to include(merge_request.title)
-      end
-
-      it 'creates system note about merge_request reassign' do
-        note = find_note('assigned to')
-
-        expect(note).not_to be_nil
-        expect(note.note).to include "assigned to #{user.to_reference} and unassigned #{user3.to_reference}"
-      end
-
       context 'with reviewers' do
         let(:opts) { { reviewer_ids: [user2.id] } }
 
@@ -664,20 +625,6 @@ RSpec.describe MergeRequests::UpdateService, :mailer do
         it 'marks previous assignee pending todos as done' do
           expect(pending_todo.reload).to be_done
         end
-
-        it 'creates a pending todo for new assignee' do
-          attributes = {
-            project: project,
-            author: user,
-            user: user2,
-            target_id: merge_request.id,
-            target_type: merge_request.class.name,
-            action: Todo::ASSIGNED,
-            state: :pending
-          }
-
-          expect(Todo.where(attributes).count).to eq 1
-        end
       end
 
       context 'when reviewers gets changed' do
@@ -999,6 +946,8 @@ RSpec.describe MergeRequests::UpdateService, :mailer do
       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])
@@ -1007,29 +956,35 @@ RSpec.describe MergeRequests::UpdateService, :mailer do
       it 'unassigns assignee when user id is 0' do
         merge_request.update!(assignee_ids: [user.id])
 
+        expect_next_instance_of(MergeRequests::HandleAssigneesChangeService, project, 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, 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 'updates the tracking when user ids are valid' do
-        expect(Gitlab::UsageDataCounters::MergeRequestActivityUniqueCounter)
-          .to receive(:track_users_assigned_to_mr)
-          .with(users: [user])
-
-        update_merge_request(assignee_ids: [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)
diff --git a/spec/workers/merge_requests/assignees_change_worker_spec.rb b/spec/workers/merge_requests/assignees_change_worker_spec.rb
index ccb0e5885ac..33478daf8d3 100644
--- a/spec/workers/merge_requests/assignees_change_worker_spec.rb
+++ b/spec/workers/merge_requests/assignees_change_worker_spec.rb
@@ -19,7 +19,7 @@ RSpec.describe MergeRequests::AssigneesChangeWorker do
   describe '#perform' do
     context 'with a non-existing merge request' do
       it 'does nothing' do
-        expect(::MergeRequests::UpdateAssigneesService).not_to receive(:new)
+        expect(::MergeRequests::HandleAssigneesChangeService).not_to receive(:new)
 
         worker.perform(non_existing_record_id, user.id, user_ids)
       end
@@ -27,7 +27,7 @@ RSpec.describe MergeRequests::AssigneesChangeWorker do
 
     context 'with a non-existing user' do
       it 'does nothing' do
-        expect(::MergeRequests::UpdateAssigneesService).not_to receive(:new)
+        expect(::MergeRequests::HandleAssigneesChangeService).not_to receive(:new)
 
         worker.perform(merge_request.id, non_existing_record_id, user_ids)
       end
@@ -35,7 +35,7 @@ RSpec.describe MergeRequests::AssigneesChangeWorker do
 
     context 'when there are no changes' do
       it 'does nothing' do
-        expect(::MergeRequests::UpdateAssigneesService).not_to receive(:new)
+        expect(::MergeRequests::HandleAssigneesChangeService).not_to receive(:new)
 
         worker.perform(merge_request.id, user.id, merge_request.assignee_ids)
       end
@@ -43,15 +43,15 @@ RSpec.describe MergeRequests::AssigneesChangeWorker do
 
     context 'when the old users cannot be found' do
       it 'does nothing' do
-        expect(::MergeRequests::UpdateAssigneesService).not_to receive(:new)
+        expect(::MergeRequests::HandleAssigneesChangeService).not_to receive(:new)
 
         worker.perform(merge_request.id, user.id, [non_existing_record_id])
       end
     end
 
     it 'gets MergeRequests::UpdateAssigneesService to handle the changes' do
-      expect_next(::MergeRequests::UpdateAssigneesService)
-        .to receive(:handle_assignee_changes).with(merge_request, match_array(old_assignees))
+      expect_next(::MergeRequests::HandleAssigneesChangeService)
+        .to receive(:execute).with(merge_request, match_array(old_assignees), execute_hooks: true)
 
       worker.perform(merge_request.id, user.id, user_ids)
     end
diff --git a/spec/workers/merge_requests/handle_assignees_change_worker_spec.rb b/spec/workers/merge_requests/handle_assignees_change_worker_spec.rb
new file mode 100644
index 00000000000..43f5196c92f
--- /dev/null
+++ b/spec/workers/merge_requests/handle_assignees_change_worker_spec.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe MergeRequests::HandleAssigneesChangeWorker do
+  include AfterNextHelpers
+
+  let_it_be(:merge_request) { create(:merge_request) }
+  let_it_be(:user) { create(:user) }
+  let_it_be(:old_assignees) { create_list(:user, 3) }
+
+  let(:user_ids) { old_assignees.map(&:id).to_a }
+  let(:options) { {} }
+  let(:worker) { described_class.new }
+
+  it_behaves_like 'an idempotent worker' do
+    let(:job_args) { [merge_request.id, user.id, user_ids, options] }
+  end
+
+  describe '#perform' do
+    it 'calls MergeRequests::HandleAssigneesChangeService#execute to handle the changes' do
+      expect_next(::MergeRequests::HandleAssigneesChangeService)
+        .to receive(:execute).with(merge_request, old_assignees, options)
+
+      worker.perform(merge_request.id, user.id, user_ids, options)
+    end
+
+    context 'when there are no changes' do
+      it 'still calls MergeRequests::HandleAssigneesChangeService#execute' do
+        expect_next(::MergeRequests::HandleAssigneesChangeService)
+          .to receive(:execute).with(merge_request, [], options)
+
+        worker.perform(merge_request.id, user.id, merge_request.assignee_ids, options)
+      end
+    end
+
+    context 'when the old assignees cannot be found' do
+      it 'still calls MergeRequests::HandleAssigneesChangeService#execute' do
+        expect_next(::MergeRequests::HandleAssigneesChangeService)
+          .to receive(:execute).with(merge_request, [], options)
+
+        worker.perform(merge_request.id, user.id, [non_existing_record_id], options)
+      end
+    end
+
+    context 'with a non-existing merge request' do
+      it 'does nothing' do
+        expect(::MergeRequests::HandleAssigneesChangeService).not_to receive(:new)
+
+        worker.perform(non_existing_record_id, user.id, user_ids, options)
+      end
+    end
+
+    context 'with a non-existing user' do
+      it 'does nothing' do
+        expect(::MergeRequests::HandleAssigneesChangeService).not_to receive(:new)
+
+        worker.perform(merge_request.id, non_existing_record_id, user_ids, options)
+      end
+    end
+  end
+end