如何使用假客戶端對 Kubernetes 整合程式碼進行單元測試？

使用 Kubernetes 的假客戶端進行單元測試

為與 Kubernetes 互動的程式碼編寫測試時，將測試環境與實際叢集隔離是有益的。這可以透過利用假客戶端來實現，這些客戶端模擬 Kubernetes API 的行為，而不需要即時叢集。

問題

考慮以下方法：

<code class="go">import (
  "fmt"
  "k8s.io/api/core/v1"
  metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
  fake "k8s.io/client-go/kubernetes/fake"
  "time"
)

func GetNamespaceCreationTime(namespace string) int64 {
  clientset, err := kubernetes.NewForConfig(rest.InClusterConfig())
  if err != nil {
    panic(err.Error())
  }
  
  ns, err := clientset.CoreV1().Namespaces().Get(namespace, metav1.GetOptions{})
  if err != nil {
    panic(err.Error())
  }
  
  fmt.Printf("%v \n", ns.CreationTimestamp)
  return (ns.GetCreationTimestamp().Unix())
}</code>

目標是使用假客戶端為此方法編寫單元測試。

解決方案

要使用假客戶端，我們需要修改GetNamespaceCreationTime 函數以接受kubernetes.Interface 作為參數:

<code class="go">func GetNamespaceCreationTime(kubeClient kubernetes.Interface, namespace string) int64 {
  ns, err := kubeClient.CoreV1().Namespaces().Get(namespace, metav1.GetOptions{})
  if err != nil {
    panic(err.Error())
  }
  
  fmt.Printf("%v \n", ns.CreationTimestamp)
  return (ns.GetCreationTimestamp().Unix())
}</code>

在我們的測試函數中，我們可以建立一個假客戶端集並將其傳遞給GetNamespaceCreationTime 方法，如下所示：

<code class="go">func TestGetNamespaceCreationTime(t *testing.T) {
  kubeClient := fake.NewSimpleClientset()
  got := GetNamespaceCreationTime(kubeClient, "default")
  want := int64(1257894000)

  nsMock :=kubeClient.CoreV1().Namespaces()
  nsMock.Create(&v1.Namespace{
    ObjectMeta: metav1.ObjectMeta{
      Name:              "default",
      CreationTimestamp: metav1.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC),
    },
  })

  if got != want {
    t.Errorf("got %q want %q", got, want)
  }
}</code>

使用叢集內配置存根完成測試

叢集內配置存根的完整測試可能如下所示：

<code class="go">import (
  "fmt"
  "k8s.io/api/core/v1"
  metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
  fake "k8s.io/client-go/kubernetes/fake"
  "k8s.io/client-go/kubernetes"
  "k8s.io/client-go/rest"
  "time"
)

var getInclusterConfigFunc = rest.InClusterConfig
var getNewKubeClientFunc = dynamic.NewForConfig

func GetNamespaceCreationTime(kubeClient kubernetes.Interface, namespace string) int64 {

  ns, err := kubeClient.CoreV1().Namespaces().Get(namespace, metav1.GetOptions{})
  if err != nil {
    panic(err.Error())
  }

  fmt.Printf("%v \n", ns.CreationTimestamp)
  return (ns.GetCreationTimestamp().Unix())
}

func GetClientSet() kubernetes.Interface {

  config, err := getInclusterConfigFunc()
  if err != nil {
    log.Warnf("Could not get in-cluster config: %s", err)
    return nil, err
  }

  client, err := getNewKubeClientFunc(config)
  if err != nil {
    log.Warnf("Could not connect to in-cluster API server: %s", err)
    return nil, err
  }

  return client, err
}

func TestGetNamespaceCreationTime(t *testing.T) {
  kubeClient := fake.NewSimpleClientset()
  got := GetNamespaceCreationTime(kubeClient, "default")
  want := int64(1257894000)

  nsMock :=kubeClient.CoreV1().Namespaces()
  nsMock.Create(&v1.Namespace{
    ObjectMeta: metav1.ObjectMeta{
      Name:              "default",
      CreationTimestamp: metav1.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC),
    },
  })

  if got != want {
    t.Errorf("got %q want %q", got, want)
  }
}

func fakeGetInclusterConfig() (*rest.Config, error) {
  return nil, nil
}

func fakeGetInclusterConfigWithError() (*rest.Config, error) {
  return nil, errors.New("fake error getting in-cluster config")
}

func TestGetInclusterKubeClient(t *testing.T) {
  origGetInclusterConfig := getInclusterConfigFunc
  getInclusterConfigFunc = fakeGetInclusterConfig
  origGetNewKubeClient := getNewKubeClientFunc
  getNewKubeClientFunc = fakeGetNewKubeClient

  defer func() {
    getInclusterConfigFunc = origGetInclusterConfig
    getNewKubeClientFunc = origGetNewKubeClient
  }()

  client, err := GetClientSet()
  assert.Nil(t, client, "Client is not nil")
  assert.Nil(t, err, "error is not nil")
}

func TestGetInclusterKubeClient_ConfigError(t *testing.T) {
  origGetInclusterConfig := getInclusterConfigFunc
  getInclusterConfigFunc = fakeGetInclusterConfigWithError

  defer func() {
    getInclusterConfigFunc = origGetInclusterConfig
  }()

  client, err := GetClientSet()
  assert.Nil(t, client, "Client is not nil")
  assert.NotNil(t, err, "error is nil")
}</code>

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