Add EE specific MetricGroup specs

ee/spec/lib/ee/gitlab/prometheus/metric_group_spec.rb

+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe Gitlab::Prometheus::MetricGroup do
+  describe '.for_project' do
+    let!(:project_metric) { create(:prometheus_metric) }
+    let!(:common_metric) { create(:prometheus_metric, :common, group: :aws_elb) }
+
+    subject do
+      described_class.for_project(project)
+        .map(&:metrics).flatten
+        .map(&:id)
+    end
+
+    context 'for current project' do
+      let(:project) { project_metric.project }
+
+      it 'returns metrics for given project and common ones' do
+        is_expected.to contain_exactly(project_metric.id, common_metric.id)
+      end
+    end
+
+    context 'for other project' do
+      let(:project) { create(:project) }
+
+      it 'returns metrics only common ones' do
+        is_expected.to contain_exactly(common_metric.id)
+      end
+    end
+  end
+end