Add delegate specs for merge request *codeclimate_artifact methods

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

spec/models/merge_request_spec.rb

@@ -2071,4 +2071,26 @@ describe MergeRequest, models: true do
 
     it { expect(subject.base_pipeline).to eq(pipeline) }
   end
+
+  describe '#base_codeclimate_artifact' do
+    before do
+      allow(subject.base_pipeline).to receive(:codeclimate_artifact).
+        and_return(1)
+    end
+
+    it 'delegates to merge request diff' do
+      expect(subject.base_codeclimate_artifact).to eq(1)
+    end
+  end
+
+  describe '#head_codeclimate_artifact' do
+    before do
+      allow(subject.head_pipeline).to receive(:codeclimate_artifact).
+        and_return(1)
+    end
+
+    it 'delegates to merge request diff' do
+      expect(subject.head_codeclimate_artifact).to eq(1)
+    end
+  end
 end