Add builds_controller_specs and spec for #trace

spec/controllers/projects/builds_controller_specs.rb

+require 'spec_helper'
+
+describe Projects::BuildsController do
+  include ApiHelpers
+
+  let(:project) { create(:empty_project, :public) }
+
+  describe 'GET trace.json' do
+    let(:pipeline) { create(:ci_pipeline, project: project) }
+    let(:build) { create(:ci_build, pipeline: pipeline) }
+    let(:user) { create(:user) }
+
+    context 'when user is logged in as developer' do
+      before do
+        project.team << [user, :developer]
+        sign_in(user)
+        get_trace
+      end
+
+      it 'traces build log' do
+        expect(response).to have_http_status(:ok)
+        expect(json_response['id']).to eq build.id
+        expect(json_response['status']).to eq build.status
+      end
+    end
+
+    context 'when user is logged in as non member' do
+      before do
+        sign_in(user)
+        get_trace
+      end
+
+      it 'traces build log' do
+        expect(response).to have_http_status(:ok)
+        expect(json_response['id']).to eq build.id
+        expect(json_response['status']).to eq build.status
+      end
+    end
+
+    def get_trace
+      get :trace, namespace_id: project.namespace,
+                  project_id: project,
+                  id: build.id,
+                  format: :json
+    end
+  end
+end