add new test cases to test json output when fetch kubeadm config from server

cmd/kubeadm/app/cmd/certs.go

@@ -26,13 +26,13 @@ import (
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/duration"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/klog/v2"
 
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmscheme "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/scheme"
 	kubeadmapiv1 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1beta3"

cmd/kubeadm/app/cmd/certs_test.go

@@ -32,11 +32,18 @@ import (
 	"testing"
 	"time"
 
+	"github.com/lithammer/dedent"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	v1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/client-go/kubernetes"
+	fakeclientset "k8s.io/client-go/kubernetes/fake"
+	clientgotesting "k8s.io/client-go/testing"
 	"k8s.io/client-go/tools/clientcmd"
 
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
@@ -45,6 +52,7 @@ import (
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	certsphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/certs"
 	kubeconfigphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/kubeconfig"
+	kubeconfigutil "k8s.io/kubernetes/cmd/kubeadm/app/util/kubeconfig"
 	"k8s.io/kubernetes/cmd/kubeadm/app/util/pkiutil"
 	testutil "k8s.io/kubernetes/cmd/kubeadm/test"
 	cmdtestutil "k8s.io/kubernetes/cmd/kubeadm/test/cmd"
@@ -492,6 +500,7 @@ func TestRunCmdCertsExpiration(t *testing.T) {
 		if err := os.RemoveAll(kdir); err != nil {
 			t.Fatalf("Failed to teardown: %s", err)
 		}
+		clientSetFromFile = kubeconfigutil.ClientSetFromFile
 	}()
 
 	cfg := testutil.GetDefaultInternalConfig(t)
@@ -555,17 +564,43 @@ kubernetesVersion: %s`,
 		cfg.CertificatesDir,
 		kubeadmconstants.MinimumControlPlaneVersion.String())
 
+	// Write the minimal kubeadm config to a file
 	customConfigPath := kdir + "/kubeadm.conf"
 	f, err := os.Create(customConfigPath)
 	require.NoError(t, err)
 	_, err = f.Write([]byte(kubeadmConfig))
 	require.NoError(t, err)
 
+	// fakeClientSetFromFile returns a fake clientset with kubeadm config map
+	var fakeClientSetFromFile = func(_ string) (kubernetes.Interface, error) {
+		client := fakeclientset.NewSimpleClientset()
+		client.PrependReactor("get", "configmaps", func(action clientgotesting.Action) (bool, runtime.Object, error) {
+			getAction := action.(clientgotesting.GetAction)
+			if getAction.GetNamespace() == metav1.NamespaceSystem && getAction.GetName() == kubeadmconstants.KubeadmConfigConfigMap {
+				cm := &v1.ConfigMap{
+					ObjectMeta: metav1.ObjectMeta{
+						Name:      kubeadmconstants.KubeadmConfigConfigMap,
+						Namespace: metav1.NamespaceSystem,
+					},
+					Data: map[string]string{
+						kubeadmconstants.ClusterConfigurationConfigMapKey: dedent.Dedent(kubeadmConfig),
+					},
+				}
+				return true, cm, nil
+			}
+			// Return an empty config map for kubelet and kube-proxy components.
+			return true, &v1.ConfigMap{}, nil
+		})
+		return client, nil
+	}
+
+	// Select a certificate used to simulate a missing certificate file
 	brokenCertName := kubeadmconstants.APIServerCertAndKeyBaseName
 	brokenCertPath, _ := pkiutil.PathsForCertAndKey(cfg.CertificatesDir, brokenCertName)
 
 	type testCase struct {
 		name           string
+		config         string
 		output         string
 		brokenCertName string
 	}
@@ -575,11 +610,17 @@ kubernetesVersion: %s`,
 		cmd := newCmdCertsExpiration(&output, kdir)
 		args := []string{
 			fmt.Sprintf("--cert-dir=%s", cfg.CertificatesDir),
-			fmt.Sprintf("--config=%s", customConfigPath),
+		}
+		if tc.config != "" {
+			args = append(args, fmt.Sprintf("--config=%s", tc.config))
+		} else {
+			clientSetFromFile = fakeClientSetFromFile
+			defer func() {
+				clientSetFromFile = kubeconfigutil.ClientSetFromFile
+			}()
 		}
 		if tc.output != "" {
 			args = append(args, fmt.Sprintf("-o=%s", tc.output))
-
 		}
 		cmd.SetArgs(args)
 		require.NoError(t, cmd.Execute())
@@ -619,21 +660,43 @@ kubernetesVersion: %s`,
 
 	testCases := []testCase{
 		{
-			name:   "print columns and no missing certs",
+			name:   "fetch kubeadm config from file and print columns and no missing certs",
+			config: customConfigPath,
 			output: "",
 		},
 		{
-			name:   "print json and no missing certs",
+			name:   "fetch kubeadm config from server and print columns and no missing certs",
+			output: "",
+		},
+		{
+			name:   "fetch kubeadm config from file and print json and no missing certs",
+			config: customConfigPath,
+			output: "json",
+		},
+		{
+			name:   "fetch kubeadm config from server and print json and no missing certs",
 			output: "json",
 		},
 		// all broken cases must be at the end of the list.
 		{
-			name:           "print columns and missing certs",
+			name:           "fetch kubeadm config from file and print columns and missing certs",
+			config:         customConfigPath,
 			output:         "",
 			brokenCertName: brokenCertName,
 		},
 		{
-			name:           "print json and missing certs",
+			name:           "fetch kubeadm config from server and print columns and missing certs",
+			output:         "",
+			brokenCertName: brokenCertName,
+		},
+		{
+			name:           "fetch kubeadm config from file and print json and missing certs",
+			config:         customConfigPath,
+			output:         "json",
+			brokenCertName: brokenCertName,
+		},
+		{
+			name:           "fetch kubeadm config from server and print json and missing certs",
 			output:         "json",
 			brokenCertName: brokenCertName,
 		},