Support merge on pipeline success w/ push options

MergeRequests::PushOptionsHandlerService has been updated to allow
creating and updating merge requests with the
`merge_when_pipeline_succeeds` set using git push options.

To create a new merge request and set it to merge when the pipeline
succeeds:

  git push -u origin -o merge_request.create \
    -o merge_request.merge_when_pipeline_succeeds

To update an existing merge request and set it to merge when the
pipeline succeeds:

  git push -u origin -o merge_request.merge_when_pipeline_succeeds

Issue https://gitlab.com/gitlab-org/gitlab-ce/issues/53198

1 files changed, 82 insertions, 0 deletions

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 96becfcae26..eafe7a34617 100644
--- a/spec/services/merge_requests/push_options_handler_service_spec.rb
+++ b/spec/services/merge_requests/push_options_handler_service_spec.rb
@@ -66,6 +66,22 @@ describe MergeRequests::PushOptionsHandlerService do
     end
   end
 
+  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
+      service.execute
+
+      expect(last_mr.merge_when_pipeline_succeeds).to eq(true)
+    end
+
+    it 'sets merge_user to the user' do
+      service.execute
+
+      expect(last_mr.merge_user).to eq(user)
+    end
+  end
+
   shared_examples_for 'a service that does not create a merge request' do
     it do
       expect { service.execute }.not_to change { MergeRequest.count }
@@ -118,6 +134,72 @@ describe MergeRequests::PushOptionsHandlerService do
     end
   end
 
+  describe '`merge_when_pipeline_succeeds` push option' do
+    let(:push_options) { { merge_when_pipeline_succeeds: true } }
+
+    context 'with a new branch' do
+      let(:changes) { new_branch_changes }
+
+      it_behaves_like 'a service that does not create a merge request'
+
+      it 'adds an error to the service' do
+        error = "A merge_request.create push option is required to create a merge request for branch #{source_branch}"
+
+        service.execute
+
+        expect(service.errors).to include(error)
+      end
+
+      context 'when coupled with the `create` push option' do
+        let(:push_options) { { create: true, merge_when_pipeline_succeeds: true } }
+
+        it_behaves_like 'a service that can create a merge request'
+        it_behaves_like 'a service that can set the merge request to merge when pipeline succeeds'
+      end
+    end
+
+    context 'with an existing branch but no open MR' do
+      let(:changes) { existing_branch_changes }
+
+      it_behaves_like 'a service that does not create a merge request'
+
+      it 'adds an error to the service' do
+        error = "A merge_request.create push option is required to create a merge request for branch #{source_branch}"
+
+        service.execute
+
+        expect(service.errors).to include(error)
+      end
+
+      context 'when coupled with the `create` push option' do
+        let(:push_options) { { create: true, merge_when_pipeline_succeeds: true } }
+
+        it_behaves_like 'a service that can create a merge request'
+        it_behaves_like 'a service that can set the merge request to merge when pipeline succeeds'
+      end
+    end
+
+    context 'with an existing branch that has a merge request open' do
+      let(:changes) { existing_branch_changes }
+      let!(:merge_request) { create(:merge_request, source_project: project, source_branch: source_branch)}
+
+      it_behaves_like 'a service that does not create a merge request'
+      it_behaves_like 'a service that can set the merge request to merge when pipeline succeeds'
+    end
+
+    context 'with a deleted branch' do
+      let(:changes) { deleted_branch_changes }
+
+      it_behaves_like 'a service that does nothing'
+    end
+
+    context 'with the project default branch' do
+      let(:changes) { default_branch_changes }
+
+      it_behaves_like 'a service that does nothing'
+    end
+  end
+
   describe '`target` push option' do
     let(:push_options) { { target: target_branch } }