Merge branch 'fix-commit-status' into 'master'

Fix an error where we were unable to create a CommitStatus for running state

Due to severe refactoring of Pipeline we introduced regression in how CommitStatus is handled. We received an report that it's impossible to create a CommitStatus with state `running` when there were not previous status. 

The support for Commit Statuses should be simplified. Right now I'm doing minimal change to move forward and fix a bug, but I'll create a new MR that will move all logic that is now part of `lib/api/commit_statuses.rb` to separate service to simplify the implementation.

This error happens due to the fact that we introduced additional status of builds: `created`.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/21345

See merge request !6107

lib/api/commit_statuses.rb

@@ -37,7 +37,7 @@ module API
       #   id (required) - The ID of a project
       #   sha (required) - The commit hash
       #   ref (optional) - The ref
-      #   state (required) - The state of the status. Can be: pending, running, success, error or failure
+      #   state (required) - The state of the status. Can be: pending, running, success, failed or canceled
       #   target_url (optional) - The target URL to associate with this status
       #   description (optional) - A short description of the status
       #   name or context (optional) - A string label to differentiate this status from the status of other systems. Default: "default"
@@ -46,7 +46,7 @@ module API
       post ':id/statuses/:sha' do
         authorize! :create_commit_status, user_project
         required_attributes! [:state]
-        attrs = attributes_for_keys [:ref, :target_url, :description, :context, :name]
+        attrs = attributes_for_keys [:target_url, :description]
         commit = @project.commit(params[:sha])
         not_found! 'Commit' unless commit
 
@@ -58,36 +58,38 @@ module API
         # the first found branch on that commit
 
         ref = params[:ref]
-        unless ref
-          branches = @project.repository.branch_names_contains(commit.sha)
-          not_found! 'References for commit' if branches.none?
-          ref = branches.first
-        end
+        ref ||= @project.repository.branch_names_contains(commit.sha).first
+        not_found! 'References for commit' unless ref
+
+        name = params[:name] || params[:context] || 'default'
 
         pipeline = @project.ensure_pipeline(commit.sha, ref, current_user)
 
-        name = params[:name] || params[:context]
-        status = GenericCommitStatus.running_or_pending.find_by(pipeline: pipeline, name: name, ref: params[:ref])
-        status ||= GenericCommitStatus.new(project: @project, pipeline: pipeline, user: current_user)
-        status.update(attrs)
+        status = GenericCommitStatus.running_or_pending.find_or_initialize_by(
+          project: @project, pipeline: pipeline,
+          user: current_user, name: name, ref: ref)
+        status.attributes = attrs
 
+        begin
           case params[:state].to_s
+          when 'pending'
+            status.enqueue!
           when 'running'
-          status.run
+            status.enqueue
+            status.run!
           when 'success'
-          status.success
+            status.success!
           when 'failed'
-          status.drop
+            status.drop!
           when 'canceled'
-          status.cancel
+            status.cancel!
           else
-          status.status = params[:state].to_s
+            render_api_error!('invalid state', 400)
           end
 
-        if status.save
           present status, with: Entities::CommitStatus
-        else
-          render_validation_error!(status)
+        rescue StateMachines::InvalidTransition => e
+          render_api_error!(e.message, 400)
         end
       end
     end

spec/requests/api/commit_statuses_spec.rb

@@ -117,19 +117,38 @@ describe API::CommitStatuses, api: true do
     let(:post_url) { "/projects/#{project.id}/statuses/#{sha}" }
 
     context 'developer user' do
-      context 'only required parameters' do
-        before { post api(post_url, developer), state: 'success' }
-
+      %w[pending running success failed canceled].each do |status|
+        context "for #{status}" do
+          context 'uses only required parameters' do
             it 'creates commit status' do
+              post api(post_url, developer), state: status
+
               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['status']).to eq(status)
               expect(json_response['name']).to eq('default')
-          expect(json_response['ref']).to be_nil
+              expect(json_response['ref']).not_to be_empty
               expect(json_response['target_url']).to be_nil
               expect(json_response['description']).to be_nil
             end
           end
+        end
+      end
+
+      context 'transitions status from pending' do
+        before do
+          post api(post_url, developer), state: 'pending'
+        end
+
+        %w[running success failed canceled].each do |status|
+          it "to #{status}" do
+            expect { post api(post_url, developer), state: status }.not_to change { CommitStatus.count }
+
+            expect(response).to have_http_status(201)
+            expect(json_response['status']).to eq(status)
+          end
+        end
+      end
 
       context 'with all optional parameters' do
         before do