add unit tests for network plugin manager metrics

pkg/kubelet/dockershim/network/BUILD

@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "go_default_library",
@@ -46,3 +46,14 @@ filegroup(
     tags = ["automanaged"],
     visibility = ["//visibility:public"],
 )
+
+go_test(
+    name = "go_default_test",
+    srcs = ["plugins_test.go"],
+    embed = [":go_default_library"],
+    deps = [
+        "//pkg/kubelet/dockershim/network/metrics:go_default_library",
+        "//staging/src/k8s.io/component-base/metrics/legacyregistry:go_default_library",
+        "//staging/src/k8s.io/component-base/metrics/testutil:go_default_library",
+    ],
+)

pkg/kubelet/dockershim/network/plugins_test.go

@@ -0,0 +1,67 @@
+// +build !dockerless
+
+/*
+Copyright 2020 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 network
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"k8s.io/component-base/metrics/legacyregistry"
+	"k8s.io/component-base/metrics/testutil"
+	"k8s.io/kubernetes/pkg/kubelet/dockershim/network/metrics"
+)
+
+func TestNetworkPluginManagerMetrics(t *testing.T) {
+	metrics.Register()
+
+	operation := "test_operation"
+	recordOperation(operation, time.Now())
+	recordError(operation)
+
+	cases := []struct {
+		metricName string
+		want       string
+	}{
+		{
+			metricName: "kubelet_network_plugin_operations_total",
+			want: `
+# HELP kubelet_network_plugin_operations_total [ALPHA] Cumulative number of network plugin operations by operation type.
+# TYPE kubelet_network_plugin_operations_total counter
+kubelet_network_plugin_operations_total{operation_type="test_operation"} 1
+`,
+		},
+		{
+			metricName: "kubelet_network_plugin_operations_errors_total",
+			want: `
+# HELP kubelet_network_plugin_operations_errors_total [ALPHA] Cumulative number of network plugin operation errors by operation type.
+# TYPE kubelet_network_plugin_operations_errors_total counter
+kubelet_network_plugin_operations_errors_total{operation_type="test_operation"} 1
+`,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.metricName, func(t *testing.T) {
+			if err := testutil.GatherAndCompare(legacyregistry.DefaultGatherer, strings.NewReader(tc.want), tc.metricName); err != nil {
+				t.Fatal(err)
+			}
+		})
+	}
+}