Fix updaing commit status with optional attributes

Passing different optional attributes in case of updating an existing
commit status should not create a new commit status with the same name.

lib/api/commit_statuses.rb

@@ -72,14 +72,15 @@ module API
         status = GenericCommitStatus.running_or_pending.find_or_initialize_by(
           project: @project,
           pipeline: pipeline,
-          user: current_user,
           name: name,
           ref: ref,
-          target_url: params[:target_url],
-          description: params[:description],
-          coverage: params[:coverage]
+          user: current_user
         )
 
+        optional_attributes =
+          attributes_for_keys(%w[target_url description coverage])
+
+        status.update(optional_attributes) if optional_attributes.any?
         render_validation_error!(status) if status.invalid?
 
         begin

spec/requests/api/commit_statuses_spec.rb

@@ -151,18 +151,16 @@ describe API::CommitStatuses, api: true do
       end
 
       context 'with all optional parameters' do
-        before do
-          optional_params = { state: 'success',
+        context 'when creating a commit status' do
+          it 'creates commit status' do
+            post api(post_url, developer), {
+              state: 'success',
               context: 'coverage',
               ref: 'develop',
               description: 'test',
               coverage: 80.0,
               target_url: 'http://gitlab.com/status' }
 
-          post api(post_url, developer), optional_params
-        end
-
-        it 'creates commit status' do
             expect(response).to have_http_status(201)
             expect(json_response['sha']).to eq(commit.id)
             expect(json_response['status']).to eq('success')
@@ -174,6 +172,41 @@ describe API::CommitStatuses, api: true do
           end
         end
 
+        context 'when updatig a commit status' do
+          before do
+            post api(post_url, developer), {
+              state: 'running',
+              context: 'coverage',
+              ref: 'develop',
+              description: 'coverage test',
+              coverage: 0.0,
+              target_url: 'http://gitlab.com/status' }
+
+            post api(post_url, developer), {
+              state: 'success',
+              name: 'coverage',
+              ref: 'develop',
+              description: 'new description',
+              coverage: 90.0 }
+          end
+
+          it 'updates a commit status' do
+            expect(response).to have_http_status(201)
+            expect(json_response['sha']).to eq(commit.id)
+            expect(json_response['status']).to eq('success')
+            expect(json_response['name']).to eq('coverage')
+            expect(json_response['ref']).to eq('develop')
+            expect(json_response['coverage']).to eq(90.0)
+            expect(json_response['description']).to eq('new description')
+            expect(json_response['target_url']).to eq('http://gitlab.com/status')
+          end
+
+          it 'does not create a new commit status' do
+            expect(CommitStatus.count).to eq 1
+          end
+        end
+      end
+
       context 'when status is invalid' do
         before { post api(post_url, developer), state: 'invalid' }