Add Prometheus client tests

spec/lib/gitlab/prometheus_client_spec.rb

@@ -119,6 +119,36 @@ describe Gitlab::PrometheusClient, lib: true do
     end
   end
 
+  describe '#series' do
+    let(:query_url) { prometheus_series_url('series_name', 'other_service') }
+
+    around do |example|
+      Timecop.freeze { example.run }
+    end
+
+    it 'calls endpoint and returns list of series' do
+      req_stub = stub_prometheus_request(query_url, body: prometheus_series('series_name'))
+      expected = prometheus_series('series_name').deep_stringify_keys['data']
+
+      expect(subject.series('series_name', 'other_service')).to eq(expected)
+
+      expect(req_stub).to have_been_requested
+    end
+  end
+
+  describe '#label_values' do
+    let(:query_url) { prometheus_label_values_url('__name__') }
+
+    it 'calls endpoint and returns label values' do
+      req_stub = stub_prometheus_request(query_url, body: prometheus_label_values)
+      expected = prometheus_label_values.deep_stringify_keys['data']
+
+      expect(subject.label_values('__name__')).to eq(expected)
+
+      expect(req_stub).to have_been_requested
+    end
+  end
+
   describe '#query_range' do
     let(:prometheus_query) { prometheus_memory_query('env-slug') }
     let(:query_url) { prometheus_query_range_url(prometheus_query) }

spec/support/prometheus_helpers.rb

@@ -36,6 +36,19 @@ module PrometheusHelpers
     "https://prometheus.example.com/api/v1/query_range?#{query}"
   end
 
+  def prometheus_label_values_url(name)
+    "https://prometheus.example.com/api/v1/label/#{name}/values"
+  end
+
+  def prometheus_series_url(*matches, start: 8.hours.ago, stop: Time.now)
+    query = {
+      match: matches,
+      start: start.to_f,
+      end: stop.to_f
+    }.to_query
+    "https://prometheus.example.com/api/v1/series?#{query}"
+  end
+
   def stub_prometheus_request(url, body: {}, status: 200)
     WebMock.stub_request(:get, url)
       .to_return({
@@ -140,4 +153,37 @@ module PrometheusHelpers
       }
     }
   end
+
+  def prometheus_label_values
+    {
+      'status': 'success',
+      'data': %w(job_adds job_controller_rate_limiter_use job_depth job_queue_latency job_work_duration_sum up)
+    }
+  end
+
+  def prometheus_series(name)
+    {
+      'status': 'success',
+      'data': [
+        {
+          '__name__': name,
+          'container_name': 'gitlab',
+          'environment': 'mattermost',
+          'id': '/docker/9953982f95cf5010dfc59d7864564d5f188aaecddeda343699783009f89db667',
+          'image': 'gitlab/gitlab-ce:8.15.4-ce.1',
+          'instance': 'minikube',
+          'job': 'kubernetes-nodes',
+          'name': 'k8s_gitlab.e6611886_mattermost-4210310111-77z8r_gitlab_2298ae6b-da24-11e6-baee-8e7f67d0eb3a_43536cb6',
+          'namespace': 'gitlab',
+          'pod_name': 'mattermost-4210310111-77z8r'
+        },
+        {
+          '__name__': name,
+          'id': '/docker',
+          'instance': 'minikube',
+          'job': 'kubernetes-nodes'
+        }
+      ]
+    }
+  end
 end