Add collector UT, and it's also an example for custom collector

staging/src/k8s.io/component-base/metrics/collector_test.go

@@ -0,0 +1,153 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package metrics
+
+import (
+	"testing"
+
+	dto "github.com/prometheus/client_model/go"
+
+	apimachineryversion "k8s.io/apimachinery/pkg/version"
+)
+
+type testCustomCollector struct {
+	BaseStableCollector
+}
+
+var (
+	currentVersion = apimachineryversion.Info{
+		Major:      "1",
+		Minor:      "17",
+		GitVersion: "v1.17.0-alpha-1.12345",
+	}
+	alphaDesc = NewDesc("metric_alpha", "alpha metric", []string{"name"}, nil,
+		ALPHA, "")
+	stableDesc = NewDesc("metric_stable", "stable metrics", []string{"name"}, nil,
+		STABLE, "")
+	deprecatedDesc = NewDesc("metric_deprecated", "stable deprecated metrics", []string{"name"}, nil,
+		STABLE, "1.17.0")
+	hiddenDesc = NewDesc("metric_hidden", "stable hidden metrics", []string{"name"}, nil,
+		STABLE, "1.16.0")
+)
+
+func (tc *testCustomCollector) DescribeWithStability(ch chan<- *Desc) {
+	ch <- alphaDesc
+	ch <- stableDesc
+	ch <- deprecatedDesc
+	ch <- hiddenDesc
+}
+
+func (tc *testCustomCollector) CollectWithStability(ch chan<- Metric) {
+	ch <- MustNewConstMetric(
+		alphaDesc,
+		GaugeValue,
+		1,
+		"value",
+	)
+	ch <- MustNewConstMetric(
+		stableDesc,
+		GaugeValue,
+		1,
+		"value",
+	)
+	ch <- MustNewConstMetric(
+		deprecatedDesc,
+		GaugeValue,
+		1,
+		"value",
+	)
+	ch <- MustNewConstMetric(
+		hiddenDesc,
+		GaugeValue,
+		1,
+		"value",
+	)
+
+}
+
+func getMetric(metrics []*dto.MetricFamily, fqName string) *dto.MetricFamily {
+	for _, m := range metrics {
+		if *m.Name == fqName {
+			return m
+		}
+	}
+
+	return nil
+}
+
+func TestBaseCustomCollector(t *testing.T) {
+	var tests = []struct {
+		name         string
+		d            *Desc
+		shouldHidden bool
+		expectedHelp string
+	}{
+		{
+			name:         "alpha metric should contains stability metadata",
+			d:            alphaDesc,
+			shouldHidden: false,
+			expectedHelp: "[ALPHA] alpha metric",
+		},
+		{
+			name:         "stable metric should contains stability metadata",
+			d:            stableDesc,
+			shouldHidden: false,
+			expectedHelp: "[STABLE] stable metrics",
+		},
+		{
+			name:         "deprecated metric should contains stability metadata",
+			d:            deprecatedDesc,
+			shouldHidden: false,
+			expectedHelp: "[STABLE] (Deprecated since 1.17.0) stable deprecated metrics",
+		},
+		{
+			name:         "hidden metric should be ignored",
+			d:            hiddenDesc,
+			shouldHidden: true,
+			expectedHelp: "[STABLE] stable hidden metrics",
+		},
+	}
+
+	registry := newKubeRegistry(currentVersion)
+	customCollector := &testCustomCollector{}
+
+	if err := registry.CustomRegister(customCollector); err != nil {
+		t.Fatalf("register collector failed with err: %v", err)
+	}
+
+	metrics, err := registry.Gather()
+	if err != nil {
+		t.Fatalf("failed to get metrics from collector, %v", err)
+	}
+
+	for _, test := range tests {
+		tc := test
+		t.Run(tc.name, func(t *testing.T) {
+			m := getMetric(metrics, tc.d.fqName)
+			if m == nil {
+				if !tc.shouldHidden {
+					t.Fatalf("Want metric: %s", tc.d.fqName)
+				}
+			} else {
+				if m.GetHelp() != tc.expectedHelp {
+					t.Fatalf("Metric(%s) HELP(%s) not contains: %s", tc.d.fqName, *m.Help, tc.expectedHelp)
+				}
+			}
+
+		})
+	}
+}