Support merge request create with push options

To create a new merge request:

  git push -u origin -o merge_request.create

To create a new merge request setting target branch:

  git push -u origin -o merge_request.create \
    -o merge_request.target=123

To update an existing merge request with a new target branch:

  git push -u origin -o merge_request.target=123

A new Gitlab::PushOptions class handles parsing and validating the push
options array. This can be the start of the standard of GitLab accepting
push options that follow namespacing rules. Rules are discussed in issue
https://gitlab.com/gitlab-org/gitlab-ce/issues/43263.

E.g. these push options:

  -o merge_request.create -o merge_request.target=123

Become parsed as:

  {
    merge_request: {
      create: true,
      target: '123',
    }
  }

And are fetched with the class via:

  push_options.get(:merge_request)
  push_options.get(:merge_request, :create)
  push_options.get(:merge_request, :target)

A new MergeRequests::PushOptionsHandlerService takes the `merge_request`
namespaced push options and handles creating and updating
merge requests.

Any errors encountered are passed to the existing `output` Hash in
Api::Internal's `post_receive` endpoint, and passed to gitlab-shell
where they're output to the user.

Issue https://gitlab.com/gitlab-org/gitlab-ce/issues/43263

1 files changed, 61 insertions, 0 deletions

diff --git a/spec/requests/api/internal_spec.rb b/spec/requests/api/internal_spec.rb
index 0919540e4ba..62ba4281df5 100644
--- a/spec/requests/api/internal_spec.rb
+++ b/spec/requests/api/internal_spec.rb
@@ -938,6 +938,67 @@ describe API::Internal do
       expect(json_response['merge_request_urls']).to eq([])
     end
 
+    it 'does not invoke MergeRequests::PushOptionsHandlerService' do
+      expect(MergeRequests::PushOptionsHandlerService).not_to receive(:new)
+
+      post api("/internal/post_receive"), params: valid_params
+    end
+
+    context 'when there are merge_request push options' do
+      before do
+        valid_params[:push_options] = ['merge_request.create']
+      end
+
+      it 'invokes MergeRequests::PushOptionsHandlerService' do
+        expect(MergeRequests::PushOptionsHandlerService).to receive(:new)
+
+        post api("/internal/post_receive"), params: valid_params
+      end
+
+      it 'links to the newly created merge request' do
+        post api("/internal/post_receive"), params: valid_params
+
+        expect(json_response['merge_request_urls']).to match [{
+          "branch_name" => "new_branch",
+          "url" => "http://#{Gitlab.config.gitlab.host}/#{project.namespace.name}/#{project.path}/merge_requests/1",
+          "new_merge_request" => false
+        }]
+      end
+
+      it 'adds errors raised from MergeRequests::PushOptionsHandlerService to warnings' do
+        expect(MergeRequests::PushOptionsHandlerService).to receive(:new).and_raise(
+          MergeRequests::PushOptionsHandlerService::Error, 'my warning'
+        )
+
+        post api("/internal/post_receive"), params: valid_params
+
+        expect(json_response['warnings']).to eq('Error encountered with push options \'merge_request.create\': my warning')
+      end
+
+      it 'adds errors on the service instance to warnings' do
+        expect_any_instance_of(
+          MergeRequests::PushOptionsHandlerService
+        ).to receive(:errors).at_least(:once).and_return(['my error'])
+
+        post api("/internal/post_receive"), params: valid_params
+
+        expect(json_response['warnings']).to eq('Error encountered with push options \'merge_request.create\': my error')
+      end
+
+      it 'adds ActiveRecord errors on invalid MergeRequest records to warnings' do
+        invalid_merge_request = MergeRequest.new
+        invalid_merge_request.errors.add(:base, 'my error')
+
+        expect_any_instance_of(
+          MergeRequests::CreateService
+        ).to receive(:execute).and_return(invalid_merge_request)
+
+        post api("/internal/post_receive"), params: valid_params
+
+        expect(json_response['warnings']).to eq('Error encountered with push options \'merge_request.create\': my error')
+      end
+    end
+
     context 'broadcast message exists' do
       let!(:broadcast_message) { create(:broadcast_message, starts_at: 1.day.ago, ends_at: 1.day.from_now ) }