1 files changed, 41 insertions, 0 deletions
diff --git a/spec/lib/gitlab/prometheus/metric_group_spec.rb b/spec/lib/gitlab/prometheus/metric_group_spec.rb
new file mode 100644
index 00000000000..e7d16e73663
--- /dev/null
+++ b/spec/lib/gitlab/prometheus/metric_group_spec.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe Gitlab::Prometheus::MetricGroup do
+  describe '.common_metrics' do
+    let!(:project_metric) { create(:prometheus_metric) }
+    let!(:common_metric_group_a) { create(:prometheus_metric, :common, group: :aws_elb) }
+    let!(:common_metric_group_b_q1) { create(:prometheus_metric, :common, group: :kubernetes) }
+    let!(:common_metric_group_b_q2) { create(:prometheus_metric, :common, group: :kubernetes) }
+
+    subject { described_class.common_metrics }
+
+    it 'returns exactly two groups' do
+      expect(subject.map(&:name)).to contain_exactly(
+        'Response metrics (AWS ELB)', 'System metrics (Kubernetes)')
+    end
+
+    it 'returns exactly three metric queries' do
+      expect(subject.map(&:metrics).flatten.map(&:id)).to contain_exactly(
+        common_metric_group_a.id, common_metric_group_b_q1.id,
+        common_metric_group_b_q2.id)
+    end
+  end
+
+  describe '.for_project' do
+    let!(:other_project) { create(:project) }
+    let!(:project_metric) { create(:prometheus_metric) }
+    let!(:common_metric) { create(:prometheus_metric, :common, group: :aws_elb) }
+
+    subject do
+      described_class.for_project(other_project)
+        .map(&:metrics).flatten
+        .map(&:id)
+    end
+
+    it 'returns exactly one common metric' do
+      is_expected.to contain_exactly(common_metric.id)
+    end
+  end
+end