1 files changed, 59 insertions, 0 deletions
diff --git a/spec/controllers/projects/prometheus/metrics_controller_spec.rb b/spec/controllers/projects/prometheus/metrics_controller_spec.rb
new file mode 100644
index 00000000000..f17f819feee
--- /dev/null
+++ b/spec/controllers/projects/prometheus/metrics_controller_spec.rb
@@ -0,0 +1,59 @@
+require 'spec_helper'
+
+describe Projects::Prometheus::MetricsController do
+  let(:user) { create(:user) }
+  let(:project) { create(:project) }
+
+  let(:prometheus_service) { double('prometheus_service') }
+
+  before do
+    allow(controller).to receive(:project).and_return(project)
+    allow(project).to receive(:find_or_initialize_service).with('prometheus').and_return(prometheus_service)
+
+    project.add_master(user)
+    sign_in(user)
+  end
+
+  describe 'GET #active_common' do
+    context 'when prometheus metrics are enabled' do
+      context 'when data is not present' do
+        before do
+          allow(prometheus_service).to receive(:matched_metrics).and_return({})
+        end
+
+        it 'returns no content response' do
+          get :active_common, project_params(format: :json)
+
+          expect(response).to have_gitlab_http_status(204)
+        end
+      end
+
+      context 'when data is available' do
+        let(:sample_response) { { some_data: 1 } }
+
+        before do
+          allow(prometheus_service).to receive(:matched_metrics).and_return(sample_response)
+        end
+
+        it 'returns no content response' do
+          get :active_common, project_params(format: :json)
+
+          expect(response).to have_gitlab_http_status(200)
+          expect(json_response).to eq(sample_response.deep_stringify_keys)
+        end
+      end
+
+      context 'when requesting non json response' do
+        it 'returns not found response' do
+          get :active_common, project_params
+
+          expect(response).to have_gitlab_http_status(404)
+        end
+      end
+    end
+  end
+
+  def project_params(opts = {})
+    opts.reverse_merge(namespace_id: project.namespace, project_id: project)
+  end
+end