Use detailed_status effectively. Remove unnecesarry context(nest). Add new context in merge_requests_controller_spec.rb and fix a bug. Correct description of spec.

app/controllers/projects/merge_requests_controller.rb

@@ -474,6 +474,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
   end
 
   def pipeline_status
+    render json: {} and return unless @merge_request.head_pipeline.present?
     render json: PipelineSerializer
       .new(project: @project, user: @current_user)
       .represent_status(@merge_request.head_pipeline)

spec/controllers/projects/builds_controller_spec.rb

@@ -11,21 +11,18 @@ describe Projects::BuildsController do
   end
 
   describe 'GET status.json' do
-    context 'when accessing status' do
-      let(:status) do
-        Gitlab::Ci::Status::Success.new(double('object'), double('user'))
-      end
+    let(:pipeline) { create(:ci_pipeline, project: project) }
+    let(:build) { create(:ci_build, pipeline: pipeline) }
+    let(:status) { build.detailed_status(double('user')) }
 
     before do
-        pipeline = create(:ci_pipeline, project: project)
-        build = create(:ci_build, pipeline: pipeline, status: :success)
       get :status, namespace_id: project.namespace,
                    project_id: project,
                    id: build.id,
                    format: :json
     end
 
-      it 'return a correct pipeline status' do
+    it 'return a detailed build status in json' do
       expect(response).to have_http_status(:ok)
       expect(json_response['text']).to eq status.text
       expect(json_response['label']).to eq status.label
@@ -34,4 +31,3 @@ describe Projects::BuildsController do
     end
   end
 end
-end

spec/controllers/projects/merge_requests_controller_spec.rb

@@ -1180,23 +1180,18 @@ describe Projects::MergeRequestsController do
   end
 
   describe 'GET pipeline_status.json' do
-    context 'when accessing pipeline_status' do
-      let(:status) do
-        Gitlab::Ci::Status::Success.new(double('object'), double('user'))
-      end
-
-      before do
+    context 'when head_pipeline exists' do
+      let!(:pipeline) do
         create(:ci_pipeline, project: merge_request.source_project,
                              ref: merge_request.source_branch,
-                             sha: merge_request.diff_head_sha,
-                             status: :success)
-        get :pipeline_status, namespace_id: project.namespace,
-                              project_id: project,
-                              id: merge_request.iid,
-                              format: :json
+                             sha: merge_request.diff_head_sha)
       end
 
-      it 'return a correct pipeline status' do
+      let(:status) { pipeline.detailed_status(double('user')) }
+
+      before { get_pipeline_status }
+
+      it 'return a detailed head_pipeline status in json' do
         expect(response).to have_http_status(:ok)
         expect(json_response['text']).to eq status.text
         expect(json_response['label']).to eq status.label
@@ -1204,5 +1199,21 @@ describe Projects::MergeRequestsController do
         expect(json_response['favicon']).to eq status.favicon
       end
     end
+
+    context 'when head_pipeline does not exist' do
+      before { get_pipeline_status }
+
+      it 'return empty' do
+        expect(response).to have_http_status(:ok)
+        expect(json_response).to be_empty
+      end
+    end
+
+    def get_pipeline_status
+      get :pipeline_status, namespace_id: project.namespace,
+                            project_id: project,
+                            id: merge_request.iid,
+                            format: :json
+    end
   end
 end

spec/controllers/projects/pipelines_controller_spec.rb

@@ -71,20 +71,17 @@ describe Projects::PipelinesController do
   end
 
   describe 'GET status.json' do
-    context 'when accessing status' do
-      let(:status) do
-        Gitlab::Ci::Status::Success.new(double('object'), double('user'))
-      end
+    let(:pipeline) { create(:ci_pipeline, project: project) }
+    let(:status) { pipeline.detailed_status(double('user')) }
 
     before do
-        pipeline = create(:ci_pipeline, project: project, status: :success)
       get :status, namespace_id: project.namespace,
                    project_id: project,
                    id: pipeline.id,
                    format: :json
     end
 
-      it 'return a correct pipeline status' do
+    it 'return a detailed pipeline status in json' do
       expect(response).to have_http_status(:ok)
       expect(json_response['text']).to eq status.text
       expect(json_response['label']).to eq status.label
@@ -93,4 +90,3 @@ describe Projects::PipelinesController do
     end
   end
 end
-end

spec/serializers/build_serializer_spec.rb

@@ -29,10 +29,8 @@ describe BuildSerializer do
 
   describe '#represent_status' do
     context 'when represents only status' do
-      let(:status) do
-        Gitlab::Ci::Status::Success.new(double('object'), double('user'))
-      end
-      let(:resource) { create(:ci_build, status: :success) }
+      let(:resource) { create(:ci_build) }
+      let(:status) { resource.detailed_status(double('user')) }
 
       subject { serializer.represent_status(resource) }
 

spec/serializers/pipeline_serializer_spec.rb

@@ -97,10 +97,8 @@ describe PipelineSerializer do
 
   describe '#represent_status' do
     context 'when represents only status' do
-      let(:status) do
-        Gitlab::Ci::Status::Success.new(double('object'), double('user'))
-      end
-      let(:resource) { create(:ci_pipeline, status: :success) }
+      let(:resource) { create(:ci_pipeline) }
+      let(:status) { resource.detailed_status(double('user')) }
 
       subject { serializer.represent_status(resource) }