Abstract auto merge processes

We have one auto merge strategy today - Merge When Pipeline
Succeeds.

In order to add more strategies for Merge Train feature,
we abstract the architecture to be more extensible.

Removed arguments

Fix spec

16 files changed, 293 insertions, 57 deletions

diff --git a/spec/controllers/projects/merge_requests_controller_spec.rb b/spec/controllers/projects/merge_requests_controller_spec.rb
index f4a18dcba51..f8c0ab55eb4 100644
--- a/spec/controllers/projects/merge_requests_controller_spec.rb
+++ b/spec/controllers/projects/merge_requests_controller_spec.rb
@@ -429,8 +429,9 @@ describe Projects::MergeRequestsController do
 
         it 'sets the MR to merge when the pipeline succeeds' do
           service = double(:merge_when_pipeline_succeeds_service)
+          allow(service).to receive(:available_for?) { true }
 
-          expect(MergeRequests::MergeWhenPipelineSucceedsService)
+          expect(AutoMerge::MergeWhenPipelineSucceedsService)
             .to receive(:new).with(project, anything, anything)
             .and_return(service)
           expect(service).to receive(:execute).with(merge_request)
@@ -713,9 +714,9 @@ describe Projects::MergeRequestsController do
     end
   end
 
-  describe 'POST cancel_merge_when_pipeline_succeeds' do
+  describe 'POST cancel_auto_merge' do
     subject do
-      post :cancel_merge_when_pipeline_succeeds,
+      post :cancel_auto_merge,
         params: {
           format: :json,
           namespace_id: merge_request.project.namespace.to_param,
@@ -725,14 +726,15 @@ describe Projects::MergeRequestsController do
         xhr: true
     end
 
-    it 'calls MergeRequests::MergeWhenPipelineSucceedsService' do
-      mwps_service = double
+    it 'calls AutoMergeService' do
+      auto_merge_service = double
 
-      allow(MergeRequests::MergeWhenPipelineSucceedsService)
+      allow(AutoMergeService)
         .to receive(:new)
-        .and_return(mwps_service)
+        .and_return(auto_merge_service)
 
-      expect(mwps_service).to receive(:cancel).with(merge_request)
+      allow(auto_merge_service).to receive(:available_strategies).with(merge_request)
+      expect(auto_merge_service).to receive(:cancel).with(merge_request)
 
       subject
     end
diff --git a/spec/factories/merge_requests.rb b/spec/factories/merge_requests.rb
index e8df5094b83..0b6a43b13a9 100644
--- a/spec/factories/merge_requests.rb
+++ b/spec/factories/merge_requests.rb
@@ -95,7 +95,8 @@ FactoryBot.define do
     end
 
     trait :merge_when_pipeline_succeeds do
-      merge_when_pipeline_succeeds true
+      auto_merge_enabled true
+      auto_merge_strategy AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS
       merge_user { author }
     end
 
diff --git a/spec/features/merge_request/user_merges_when_pipeline_succeeds_spec.rb b/spec/features/merge_request/user_merges_when_pipeline_succeeds_spec.rb
index d4ad11b3585..e7b92dc5535 100644
--- a/spec/features/merge_request/user_merges_when_pipeline_succeeds_spec.rb
+++ b/spec/features/merge_request/user_merges_when_pipeline_succeeds_spec.rb
@@ -74,11 +74,12 @@ describe 'Merge request > User merges when pipeline succeeds', :js do
                    source_project: project,
                    title: 'Bug NS-04',
                    author: user,
-                   merge_user: user,
-                   merge_params: { force_remove_source_branch: '1' })
+                   merge_user: user)
         end
 
         before do
+          merge_request.merge_params['force_remove_source_branch'] = '0'
+          merge_request.save!
           click_link "Cancel automatic merge"
         end
 
@@ -102,11 +103,11 @@ describe 'Merge request > User merges when pipeline succeeds', :js do
 
   context 'when merge when pipeline succeeds is enabled' do
     let(:merge_request) do
-      create(:merge_request_with_diffs, :simple,  source_project: project,
-                                                  author: user,
-                                                  merge_user: user,
-                                                  title: 'MepMep',
-                                                  merge_when_pipeline_succeeds: true)
+      create(:merge_request_with_diffs, :simple, :merge_when_pipeline_succeeds,
+        source_project: project,
+        author: user,
+        merge_user: user,
+        title: 'MepMep')
     end
     let!(:build) do
       create(:ci_build, pipeline: pipeline)
diff --git a/spec/features/merge_request/user_sees_merge_widget_spec.rb b/spec/features/merge_request/user_sees_merge_widget_spec.rb
index 93ddde623fe..1477307ed7b 100644
--- a/spec/features/merge_request/user_sees_merge_widget_spec.rb
+++ b/spec/features/merge_request/user_sees_merge_widget_spec.rb
@@ -314,7 +314,8 @@ describe 'Merge request > User sees merge widget', :js do
   context 'view merge request with MWPS enabled but automatically merge fails' do
     before do
       merge_request.update(
-        merge_when_pipeline_succeeds: true,
+        auto_merge_enabled: true,
+        auto_merge_strategy: AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS,
         merge_user: merge_request.author,
         merge_error: 'Something went wrong'
       )
diff --git a/spec/frontend/vue_mr_widget/stores/get_state_key_spec.js b/spec/frontend/vue_mr_widget/stores/get_state_key_spec.js
index b356ea85cad..9797549498b 100644
--- a/spec/frontend/vue_mr_widget/stores/get_state_key_spec.js
+++ b/spec/frontend/vue_mr_widget/stores/get_state_key_spec.js
@@ -31,7 +31,7 @@ describe('getStateKey', () => {
 
     expect(bound()).toEqual('notAllowedToMerge');
 
-    context.mergeWhenPipelineSucceeds = true;
+    context.autoMergeEnabled = true;
 
     expect(bound()).toEqual('mergeWhenPipelineSucceeds');
 
diff --git a/spec/javascripts/vue_mr_widget/components/states/mr_widget_ready_to_merge_spec.js b/spec/javascripts/vue_mr_widget/components/states/mr_widget_ready_to_merge_spec.js
index 368c997d318..daca51c6156 100644
--- a/spec/javascripts/vue_mr_widget/components/states/mr_widget_ready_to_merge_spec.js
+++ b/spec/javascripts/vue_mr_widget/components/states/mr_widget_ready_to_merge_spec.js
@@ -80,7 +80,7 @@ describe('ReadyToMerge', () => {
     it('should have default data', () => {
       expect(vm.mergeWhenBuildSucceeds).toBeFalsy();
       expect(vm.useCommitMessageWithDescription).toBeFalsy();
-      expect(vm.setToMergeWhenPipelineSucceeds).toBeFalsy();
+      expect(vm.setToAutoMerge).toBeFalsy();
       expect(vm.showCommitMessageEditor).toBeFalsy();
       expect(vm.isMakingRequest).toBeFalsy();
       expect(vm.isMergingImmediately).toBeFalsy();
@@ -91,17 +91,17 @@ describe('ReadyToMerge', () => {
   });
 
   describe('computed', () => {
-    describe('shouldShowMergeWhenPipelineSucceedsText', () => {
+    describe('shouldShowAutoMergeText', () => {
       it('should return true with active pipeline', () => {
         vm.mr.isPipelineActive = true;
 
-        expect(vm.shouldShowMergeWhenPipelineSucceedsText).toBeTruthy();
+        expect(vm.shouldShowAutoMergeText).toBeTruthy();
       });
 
       it('should return false with inactive pipeline', () => {
         vm.mr.isPipelineActive = false;
 
-        expect(vm.shouldShowMergeWhenPipelineSucceedsText).toBeFalsy();
+        expect(vm.shouldShowAutoMergeText).toBeFalsy();
       });
     });
 
@@ -325,7 +325,7 @@ describe('ReadyToMerge', () => {
         vm.handleMergeButtonClick(true);
 
         setTimeout(() => {
-          expect(vm.setToMergeWhenPipelineSucceeds).toBeTruthy();
+          expect(vm.setToAutoMerge).toBeTruthy();
           expect(vm.isMakingRequest).toBeTruthy();
           expect(eventHub.$emit).toHaveBeenCalledWith('MRWidgetUpdateRequested');
 
@@ -345,7 +345,7 @@ describe('ReadyToMerge', () => {
         vm.handleMergeButtonClick(false, true);
 
         setTimeout(() => {
-          expect(vm.setToMergeWhenPipelineSucceeds).toBeFalsy();
+          expect(vm.setToAutoMerge).toBeFalsy();
           expect(vm.isMakingRequest).toBeTruthy();
           expect(eventHub.$emit).toHaveBeenCalledWith('FailedToMerge', undefined);
 
@@ -363,7 +363,7 @@ describe('ReadyToMerge', () => {
         vm.handleMergeButtonClick();
 
         setTimeout(() => {
-          expect(vm.setToMergeWhenPipelineSucceeds).toBeFalsy();
+          expect(vm.setToAutoMerge).toBeFalsy();
           expect(vm.isMakingRequest).toBeTruthy();
           expect(vm.initiateMergePolling).toHaveBeenCalled();
 
diff --git a/spec/models/merge_request_spec.rb b/spec/models/merge_request_spec.rb
index c72b6e9033d..43c61c48fe5 100644
--- a/spec/models/merge_request_spec.rb
+++ b/spec/models/merge_request_spec.rb
@@ -1038,14 +1038,28 @@ describe MergeRequest do
     end
   end
 
-  describe "#reset_merge_when_pipeline_succeeds" do
+  describe "#auto_merge_strategy" do
+    subject { merge_request.auto_merge_strategy }
+
+    let(:merge_request) { create(:merge_request, :merge_when_pipeline_succeeds) }
+
+    it { is_expected.to eq('merge_when_pipeline_succeeds') }
+
+    context 'when auto merge is disabled' do
+      let(:merge_request) { create(:merge_request) }
+
+      it { is_expected.to be_nil }
+    end
+  end
+
+  describe "#reset_auto_merge" do
     let(:merge_if_green) do
       create :merge_request, merge_when_pipeline_succeeds: true, merge_user: create(:user),
                              merge_params: { "should_remove_source_branch" => "1", "commit_message" => "msg" }
     end
 
     it "sets the item to false" do
-      merge_if_green.reset_merge_when_pipeline_succeeds
+      merge_if_green.reset_auto_merge
       merge_if_green.reload
 
       expect(merge_if_green.merge_when_pipeline_succeeds).to be_falsey
diff --git a/spec/presenters/merge_request_presenter_spec.rb b/spec/presenters/merge_request_presenter_spec.rb
index 0e1aed42cc5..6408b0bd748 100644
--- a/spec/presenters/merge_request_presenter_spec.rb
+++ b/spec/presenters/merge_request_presenter_spec.rb
@@ -207,25 +207,25 @@ describe MergeRequestPresenter do
     end
   end
 
-  describe '#cancel_merge_when_pipeline_succeeds_path' do
+  describe '#cancel_auto_merge_path' do
     subject do
       described_class.new(resource, current_user: user)
-        .cancel_merge_when_pipeline_succeeds_path
+        .cancel_auto_merge_path
     end
 
     context 'when can cancel mwps' do
       it 'returns path' do
-        allow(resource).to receive(:can_cancel_merge_when_pipeline_succeeds?)
+        allow(resource).to receive(:can_cancel_auto_merge?)
           .with(user)
           .and_return(true)
 
-        is_expected.to eq("/#{resource.project.full_path}/merge_requests/#{resource.iid}/cancel_merge_when_pipeline_succeeds")
+        is_expected.to eq("/#{resource.project.full_path}/merge_requests/#{resource.iid}/cancel_auto_merge")
       end
     end
 
     context 'when cannot cancel mwps' do
       it 'returns nil' do
-        allow(resource).to receive(:can_cancel_merge_when_pipeline_succeeds?)
+        allow(resource).to receive(:can_cancel_auto_merge?)
           .with(user)
           .and_return(false)
 
diff --git a/spec/requests/api/merge_requests_spec.rb b/spec/requests/api/merge_requests_spec.rb
index 5c94a87529b..9f9180bc8c9 100644
--- a/spec/requests/api/merge_requests_spec.rb
+++ b/spec/requests/api/merge_requests_spec.rb
@@ -1473,7 +1473,7 @@ describe API::MergeRequests do
     end
 
     it "enables merge when pipeline succeeds if the pipeline is active" do
-      allow_any_instance_of(MergeRequest).to receive(:head_pipeline).and_return(pipeline)
+      allow_any_instance_of(MergeRequest).to receive_messages(head_pipeline: pipeline, actual_head_pipeline: pipeline)
       allow(pipeline).to receive(:active?).and_return(true)
 
       put api("/projects/#{project.id}/merge_requests/#{merge_request.iid}/merge", user), params: { merge_when_pipeline_succeeds: true }
@@ -1484,7 +1484,7 @@ describe API::MergeRequests do
     end
 
     it "enables merge when pipeline succeeds if the pipeline is active and only_allow_merge_if_pipeline_succeeds is true" do
-      allow_any_instance_of(MergeRequest).to receive(:head_pipeline).and_return(pipeline)
+      allow_any_instance_of(MergeRequest).to receive_messages(head_pipeline: pipeline, actual_head_pipeline: pipeline)
       allow(pipeline).to receive(:active?).and_return(true)
       project.update_attribute(:only_allow_merge_if_pipeline_succeeds, true)
 
@@ -1950,7 +1950,7 @@ describe API::MergeRequests do
 
   describe 'POST :id/merge_requests/:merge_request_iid/cancel_merge_when_pipeline_succeeds' do
     before do
-      ::MergeRequests::MergeWhenPipelineSucceedsService.new(merge_request.target_project, user).execute(merge_request)
+      ::AutoMergeService.new(merge_request.target_project, user).execute(merge_request, AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS)
     end
 
     it 'removes the merge_when_pipeline_succeeds status' do
diff --git a/spec/serializers/merge_request_widget_entity_spec.rb b/spec/serializers/merge_request_widget_entity_spec.rb
index b89898f26f7..a27c22191f4 100644
--- a/spec/serializers/merge_request_widget_entity_spec.rb
+++ b/spec/serializers/merge_request_widget_entity_spec.rb
@@ -297,4 +297,50 @@ describe MergeRequestWidgetEntity do
       end
     end
   end
+
+  describe 'auto merge' do
+    context 'when auto merge is enabled' do
+      let(:resource) { create(:merge_request, :merge_when_pipeline_succeeds) }
+
+      it 'returns auto merge related information' do
+        expect(subject[:auto_merge_enabled]).to be_truthy
+        expect(subject[:auto_merge_strategy]).to eq('merge_when_pipeline_succeeds')
+      end
+    end
+
+    context 'when auto merge is not enabled' do
+      let(:resource) { create(:merge_request) }
+
+      it 'returns auto merge related information' do
+        expect(subject[:auto_merge_enabled]).to be_falsy
+        expect(subject[:auto_merge_strategy]).to be_nil
+      end
+    end
+
+    context 'when head pipeline is running' do
+      before do
+        create(:ci_pipeline, :running, project: project,
+                                       ref: resource.source_branch,
+                                       sha: resource.diff_head_sha)
+        resource.update_head_pipeline
+      end
+
+      it 'returns available auto merge strategies' do
+        expect(subject[:available_auto_merge_strategies]).to eq(%w[merge_when_pipeline_succeeds])
+      end
+    end
+
+    context 'when head pipeline is finished' do
+      before do
+        create(:ci_pipeline, :success, project: project,
+                                       ref: resource.source_branch,
+                                       sha: resource.diff_head_sha)
+        resource.update_head_pipeline
+      end
+
+      it 'returns available auto merge strategies' do
+        expect(subject[:available_auto_merge_strategies]).to be_empty
+      end
+    end
+  end
 end
diff --git a/spec/services/merge_requests/merge_when_pipeline_succeeds_service_spec.rb b/spec/services/auto_merge/merge_when_pipeline_succeeds_service_spec.rb
index 96f61f3f103..a20bf8e17e4 100644
--- a/spec/services/merge_requests/merge_when_pipeline_succeeds_service_spec.rb
+++ b/spec/services/auto_merge/merge_when_pipeline_succeeds_service_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe MergeRequests::MergeWhenPipelineSucceedsService do
+describe AutoMerge::MergeWhenPipelineSucceedsService do
   let(:user) { create(:user) }
   let(:project) { create(:project, :repository) }
 
@@ -21,6 +21,27 @@ describe MergeRequests::MergeWhenPipelineSucceedsService do
     described_class.new(project, user, commit_message: 'Awesome message')
   end
 
+  describe "#available_for?" do
+    subject { service.available_for?(mr_merge_if_green_enabled) }
+
+    let(:pipeline_status) { :running }
+
+    before do
+      create(:ci_pipeline, pipeline_status, ref: mr_merge_if_green_enabled.source_branch,
+                                            sha: mr_merge_if_green_enabled.diff_head_sha,
+                                            project: mr_merge_if_green_enabled.source_project)
+      mr_merge_if_green_enabled.update_head_pipeline
+    end
+
+    it { is_expected.to be_truthy }
+
+    context 'when the head piipeline succeeded' do
+      let(:pipeline_status) { :success }
+
+      it { is_expected.to be_falsy }
+    end
+  end
+
   describe "#execute" do
     let(:merge_request) do
       create(:merge_request, target_project: project, source_project: project,
@@ -30,8 +51,7 @@ describe MergeRequests::MergeWhenPipelineSucceedsService do
     context 'first time enabling' do
       before do
         allow(merge_request)
-          .to receive(:head_pipeline)
-          .and_return(pipeline)
+          .to receive_messages(head_pipeline: pipeline, actual_head_pipeline: pipeline)
 
         service.execute(merge_request)
       end
@@ -39,7 +59,7 @@ describe MergeRequests::MergeWhenPipelineSucceedsService do
       it 'sets the params, merge_user, and flag' do
         expect(merge_request).to be_valid
         expect(merge_request.merge_when_pipeline_succeeds).to be_truthy
-        expect(merge_request.merge_params).to eq commit_message: 'Awesome message'
+        expect(merge_request.merge_params).to include commit_message: 'Awesome message'
         expect(merge_request.merge_user).to be user
       end
 
@@ -54,8 +74,8 @@ describe MergeRequests::MergeWhenPipelineSucceedsService do
       let(:build)   { create(:ci_build, ref: mr_merge_if_green_enabled.source_branch) }
 
       before do
-        allow(mr_merge_if_green_enabled).to receive(:head_pipeline)
-          .and_return(pipeline)
+        allow(mr_merge_if_green_enabled)
+          .to receive_messages(head_pipeline: pipeline, actual_head_pipeline: pipeline)
 
         allow(mr_merge_if_green_enabled).to receive(:mergeable?)
           .and_return(true)
@@ -72,7 +92,7 @@ describe MergeRequests::MergeWhenPipelineSucceedsService do
     end
   end
 
-  describe "#trigger" do
+  describe "#process" do
     let(:merge_request_ref) { mr_merge_if_green_enabled.source_branch }
     let(:merge_request_head) do
       project.commit(mr_merge_if_green_enabled.source_branch).id
@@ -86,8 +106,11 @@ describe MergeRequests::MergeWhenPipelineSucceedsService do
       end
 
       it "merges all merge requests with merge when the pipeline succeeds enabled" do
+        allow(mr_merge_if_green_enabled)
+          .to receive_messages(head_pipeline: triggering_pipeline, actual_head_pipeline: triggering_pipeline)
+
         expect(MergeWorker).to receive(:perform_async)
-        service.trigger(triggering_pipeline)
+        service.process(mr_merge_if_green_enabled)
       end
     end
 
@@ -99,7 +122,7 @@ describe MergeRequests::MergeWhenPipelineSucceedsService do
 
       it 'does not merge request' do
         expect(MergeWorker).not_to receive(:perform_async)
-        service.trigger(old_pipeline)
+        service.process(mr_merge_if_green_enabled)
       end
     end
 
@@ -111,7 +134,7 @@ describe MergeRequests::MergeWhenPipelineSucceedsService do
 
       it 'does not merge request' do
         expect(MergeWorker).not_to receive(:perform_async)
-        service.trigger(unrelated_pipeline)
+        service.process(mr_merge_if_green_enabled)
       end
     end
 
@@ -125,8 +148,11 @@ describe MergeRequests::MergeWhenPipelineSucceedsService do
       end
 
       it 'merges the associated merge request' do
+        allow(mr_merge_if_green_enabled)
+          .to receive_messages(head_pipeline: pipeline, actual_head_pipeline: pipeline)
+
         expect(MergeWorker).to receive(:perform_async)
-        service.trigger(pipeline)
+        service.process(mr_merge_if_green_enabled)
       end
     end
   end
diff --git a/spec/services/auto_merge_service_spec.rb b/spec/services/auto_merge_service_spec.rb
new file mode 100644
index 00000000000..d0eefed3150
--- /dev/null
+++ b/spec/services/auto_merge_service_spec.rb
@@ -0,0 +1,140 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe AutoMergeService do
+  set(:project) { create(:project) }
+  set(:user) { create(:user) }
+  let(:service) { described_class.new(project, user) }
+
+  describe '.all_strategies' do
+    subject { described_class.all_strategies }
+
+    it 'returns all strategies' do
+      is_expected.to eq(AutoMergeService::STRATEGIES)
+    end
+  end
+
+  describe '#available_strategies' do
+    subject { service.available_strategies(merge_request) }
+
+    let(:merge_request) { create(:merge_request) }
+    let(:pipeline_status) { :running }
+
+    before do
+      create(:ci_pipeline, pipeline_status, ref: merge_request.source_branch,
+                                            sha: merge_request.diff_head_sha,
+                                            project: merge_request.source_project)
+
+      merge_request.update_head_pipeline
+    end
+
+    it 'returns available strategies' do
+      is_expected.to include('merge_when_pipeline_succeeds')
+    end
+
+    context 'when the head piipeline succeeded' do
+      let(:pipeline_status) { :success }
+
+      it 'returns available strategies' do
+        is_expected.to be_empty
+      end
+    end
+  end
+
+  describe '.get_service_class' do
+    subject { described_class.get_service_class(strategy) }
+
+    let(:strategy) { AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS }
+
+    it 'returns service instance' do
+      is_expected.to eq(AutoMerge::MergeWhenPipelineSucceedsService)
+    end
+
+    context 'when strategy is not present' do
+      let(:strategy) { }
+
+      it 'returns nil' do
+        is_expected.to be_nil
+      end
+    end
+  end
+
+  describe '#execute' do
+    subject { service.execute(merge_request, strategy) }
+
+    let(:merge_request) { create(:merge_request) }
+    let(:pipeline_status) { :running }
+    let(:strategy) { AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS }
+
+    before do
+      create(:ci_pipeline, pipeline_status, ref: merge_request.source_branch,
+                                            sha: merge_request.diff_head_sha,
+                                            project: merge_request.source_project)
+
+      merge_request.update_head_pipeline
+    end
+
+    it 'delegates to a relevant service instance' do
+      expect_next_instance_of(AutoMerge::MergeWhenPipelineSucceedsService) do |service|
+        expect(service).to receive(:execute).with(merge_request)
+      end
+
+      subject
+    end
+
+    context 'when the head piipeline succeeded' do
+      let(:pipeline_status) { :success }
+
+      it 'returns failed' do
+        is_expected.to eq(:failed)
+      end
+    end
+  end
+
+  describe '#process' do
+    subject { service.process(merge_request) }
+
+    let(:merge_request) { create(:merge_request, :merge_when_pipeline_succeeds) }
+
+    it 'delegates to a relevant service instance' do
+      expect_next_instance_of(AutoMerge::MergeWhenPipelineSucceedsService) do |service|
+        expect(service).to receive(:process).with(merge_request)
+      end
+
+      subject
+    end
+
+    context 'when auto merge is not enabled' do
+      let(:merge_request) { create(:merge_request) }
+
+      it 'returns nil' do
+        is_expected.to be_nil
+      end
+    end
+  end
+
+  describe '#cancel' do
+    subject { service.cancel(merge_request) }
+
+    let(:merge_request) { create(:merge_request, :merge_when_pipeline_succeeds) }
+
+    it 'delegates to a relevant service instance' do
+      expect_next_instance_of(AutoMerge::MergeWhenPipelineSucceedsService) do |service|
+        expect(service).to receive(:cancel).with(merge_request)
+      end
+
+      subject
+    end
+
+    context 'when auto merge is not enabled' do
+      let(:merge_request) { create(:merge_request) }
+
+      it 'returns error' do
+        expect(subject[:message]).to eq("Can't cancel the automatic merge")
+        expect(subject[:status]).to eq(:error)
+        expect(subject[:http_status]).to eq(406)
+      end
+    end
+  end
+end
diff --git a/spec/services/merge_requests/push_options_handler_service_spec.rb b/spec/services/merge_requests/push_options_handler_service_spec.rb
index f7a39bb42d5..54b9c6dae38 100644
--- a/spec/services/merge_requests/push_options_handler_service_spec.rb
+++ b/spec/services/merge_requests/push_options_handler_service_spec.rb
@@ -76,10 +76,11 @@ describe MergeRequests::PushOptionsHandlerService do
   shared_examples_for 'a service that can set the merge request to merge when pipeline succeeds' do
     subject(:last_mr) { MergeRequest.last }
 
-    it 'sets merge_when_pipeline_succeeds' do
+    it 'sets auto_merge_enabled' do
       service.execute
 
-      expect(last_mr.merge_when_pipeline_succeeds).to eq(true)
+      expect(last_mr.auto_merge_enabled).to eq(true)
+      expect(last_mr.auto_merge_strategy).to eq(AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS)
     end
 
     it 'sets merge_user to the user' do
diff --git a/spec/services/merge_requests/refresh_service_spec.rb b/spec/services/merge_requests/refresh_service_spec.rb
index 7258428589f..6ba67c7165c 100644
--- a/spec/services/merge_requests/refresh_service_spec.rb
+++ b/spec/services/merge_requests/refresh_service_spec.rb
@@ -23,7 +23,8 @@ describe MergeRequests::RefreshService do
                               source_branch: 'master',
                               target_branch: 'feature',
                               target_project: @project,
-                              merge_when_pipeline_succeeds: true,
+                              auto_merge_enabled: true,
+                              auto_merge_strategy: AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS,
                               merge_user: @user)
 
       @another_merge_request = create(:merge_request,
@@ -31,7 +32,8 @@ describe MergeRequests::RefreshService do
                                       source_branch: 'master',
                                       target_branch: 'test',
                                       target_project: @project,
-                                      merge_when_pipeline_succeeds: true,
+                                      auto_merge_enabled: true,
+                                      auto_merge_strategy: AutoMergeService::STRATEGY_MERGE_WHEN_PIPELINE_SUCCEEDS,
                                       merge_user: @user)
 
       @fork_merge_request = create(:merge_request,
@@ -83,7 +85,7 @@ describe MergeRequests::RefreshService do
 
         expect(@merge_request.notes).not_to be_empty
         expect(@merge_request).to be_open
-        expect(@merge_request.merge_when_pipeline_succeeds).to be_falsey
+        expect(@merge_request.auto_merge_enabled).to be_falsey
         expect(@merge_request.diff_head_sha).to eq(@newrev)
         expect(@fork_merge_request).to be_open
         expect(@fork_merge_request.notes).to be_empty
@@ -292,7 +294,7 @@ describe MergeRequests::RefreshService do
 
         expect(@merge_request.notes).not_to be_empty
         expect(@merge_request).to be_open
-        expect(@merge_request.merge_when_pipeline_succeeds).to be_falsey
+        expect(@merge_request.auto_merge_enabled).to be_falsey
         expect(@merge_request.diff_head_sha).to eq(@newrev)
         expect(@fork_merge_request).to be_open
         expect(@fork_merge_request.notes).to be_empty
diff --git a/spec/services/merge_requests/update_service_spec.rb b/spec/services/merge_requests/update_service_spec.rb
index ba4c9ce60f3..fbfcd95e204 100644
--- a/spec/services/merge_requests/update_service_spec.rb
+++ b/spec/services/merge_requests/update_service_spec.rb
@@ -217,8 +217,9 @@ describe MergeRequests::UpdateService, :mailer do
             head_pipeline_of: merge_request
           )
 
-          expect(MergeRequests::MergeWhenPipelineSucceedsService).to receive(:new).with(project, user)
+          expect(AutoMerge::MergeWhenPipelineSucceedsService).to receive(:new).with(project, user, {})
             .and_return(service_mock)
+          allow(service_mock).to receive(:available_for?) { true }
           expect(service_mock).to receive(:execute).with(merge_request)
         end
 
diff --git a/spec/workers/pipeline_success_worker_spec.rb b/spec/workers/pipeline_success_worker_spec.rb
index 4cbe384b47a..b511edfa620 100644
--- a/spec/workers/pipeline_success_worker_spec.rb
+++ b/spec/workers/pipeline_success_worker_spec.rb
@@ -5,12 +5,13 @@ require 'spec_helper'
 describe PipelineSuccessWorker do
   describe '#perform' do
     context 'when pipeline exists' do
-      let(:pipeline) { create(:ci_pipeline, status: 'success') }
+      let(:pipeline) { create(:ci_pipeline, status: 'success', ref: merge_request.source_branch, project: merge_request.source_project) }
+      let(:merge_request) { create(:merge_request) }
 
       it 'performs "merge when pipeline succeeds"' do
-        expect_any_instance_of(
-          MergeRequests::MergeWhenPipelineSucceedsService
-        ).to receive(:trigger)
+        expect_next_instance_of(AutoMergeService) do |auto_merge|
+          expect(auto_merge).to receive(:process)
+        end
 
         described_class.new.perform(pipeline.id)
       end