add test

staging/src/k8s.io/component-base/metrics/legacyregistry/registry_test.go

@@ -0,0 +1,43 @@
+/*
+Copyright 2023 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 legacyregistry
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"testing"
+	"time"
+)
+
+const (
+	processStartTimeHeader = "Process-Start-Time-Unix"
+)
+
+func TestProcessStartTimeHeader(t *testing.T) {
+	now := time.Now()
+	handler := Handler()
+
+	request, _ := http.NewRequest("GET", "/", nil)
+	writer := httptest.NewRecorder()
+	handler.ServeHTTP(writer, request)
+	got := writer.Header().Get(processStartTimeHeader)
+	gotInt, _ := strconv.ParseInt(got, 10, 64)
+	if gotInt != now.Unix() {
+		t.Errorf("got %d, wanted %d", gotInt, now.Unix())
+	}
+}