Cluster controller tests

app/controllers/projects/clusters_controller.rb

@@ -64,7 +64,7 @@ class Projects::ClustersController < Projects::ApplicationController
   end
 
   def metrics
-    render_404 unless prometheus_adapter&.can_query?
+    return render_404 unless prometheus_adapter&.can_query?
 
     respond_to do |format|
       format.json do

spec/controllers/projects/clusters_controller_spec.rb

@@ -149,6 +149,92 @@ describe Projects::ClustersController do
     end
   end
 
+  describe 'GET metrics' do
+    let(:cluster) { create(:cluster, :provided_by_gcp, projects: [project]) }
+
+    describe 'functionality' do
+      let(:user) { create(:user) }
+
+      before do
+        project.add_master(user)
+        sign_in(user)
+      end
+
+      context "Can't query Prometheus" do
+        it 'returns not found' do
+          go
+
+          expect(response).to have_gitlab_http_status(:not_found)
+        end
+      end
+
+      context 'can query Prometheus' do
+        let(:prometheus_adapter) { double('prometheus_adapter', can_query?: true, query: nil) }
+
+        before do
+          allow(controller).to receive(:prometheus_adapter).and_return(prometheus_adapter)
+        end
+
+        it 'queries cluster metrics' do
+          go
+
+          expect(prometheus_adapter).to have_received(:query).with(:cluster)
+        end
+
+        context 'when response has content' do
+          let(:query_response) { { response: nil } }
+
+          before do
+            allow(prometheus_adapter).to receive(:query).and_return(query_response)
+          end
+
+          it 'returns prometheus query response' do
+            go
+
+            expect(response).to have_gitlab_http_status(:ok)
+            expect(response.body).to eq(query_response)
+          end
+        end
+
+        context 'when response has no content' do
+          let(:query_response) { {} }
+
+          before do
+            allow(prometheus_adapter).to receive(:query).and_return(query_response)
+          end
+
+          it 'returns prometheus query response' do
+            go
+
+            expect(response).to have_gitlab_http_status(:no_content)
+          end
+        end
+      end
+    end
+
+    def go
+      get :metrics, format: :json, namespace_id: project.namespace,
+          project_id: project,
+          id: cluster
+    end
+
+    describe 'security' do
+      let(:prometheus_adapter) { double('prometheus_adapter', can_query?: true, query: nil) }
+      before do
+        allow(controller).to receive(:prometheus_adapter).and_return(prometheus_adapter)
+      end
+
+      it { expect { go }.to be_allowed_for(:admin) }
+      it { expect { go }.to be_allowed_for(:owner).of(project) }
+      it { expect { go }.to be_allowed_for(:master).of(project) }
+      it { expect { go }.to be_denied_for(:developer).of(project) }
+      it { expect { go }.to be_denied_for(:reporter).of(project) }
+      it { expect { go }.to be_denied_for(:guest).of(project) }
+      it { expect { go }.to be_denied_for(:user) }
+      it { expect { go }.to be_denied_for(:external) }
+    end
+  end
+
   describe 'PUT update' do
     context 'when cluster is provided by GCP' do
       let(:cluster) { create(:cluster, :provided_by_gcp, projects: [project]) }