Fix update-context to use KUBECONFIG when the env is set and add integration test

cmd/minikube/cmd/update-context.go

@@ -17,6 +17,8 @@ limitations under the License.
 package cmd
 
 import (
+	"os"
+
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 	"k8s.io/minikube/pkg/minikube/cluster"
@@ -45,7 +47,13 @@ var updateContextCmd = &cobra.Command{
 		if err != nil {
 			exit.WithError("Error host driver ip status", err)
 		}
-		updated, err := kubeconfig.UpdateIP(ip, machineName, constants.KubeconfigPath)
+		updated := false
+		kubeConfigPath := os.Getenv("KUBECONFIG")
+		if kubeConfigPath == "" {
+			updated, err = kubeconfig.UpdateIP(ip, machineName, constants.KubeconfigPath)
+		} else {
+			updated, err = kubeconfig.UpdateIP(ip, machineName, kubeConfigPath)
+		}
 		if err != nil {
 			exit.WithError("update config", err)
 		}

test/integration/functional_test.go

@@ -103,6 +103,7 @@ func TestFunctional(t *testing.T) {
 			{"SSHCmd", validateSSHCmd},
 			{"MySQL", validateMySQL},
 			{"FileSync", validateFileSync},
+			{"UpdateContextCmd", validateUpdateContextCmd},
 		}
 		for _, tc := range tests {
 			tc := tc
@@ -645,6 +646,19 @@ func validateFileSync(ctx context.Context, t *testing.T, profile string) {
 	}
 }
 
+// validateUpdateContextCmd asserts basic "update-context" command functionality
+func validateUpdateContextCmd(ctx context.Context, t *testing.T, profile string) {
+	rr, err := Run(t, exec.CommandContext(ctx, Target(), "-p", profile, "update-context", "--alsologtostderr", "-v=2"))
+	if err != nil {
+		t.Errorf("%s failed: %v", rr.Args, err)
+	}
+
+	want := []byte("IP was already correctly configured")
+	if !bytes.Contains(rr.Stdout.Bytes(), want) {
+		t.Errorf("update-context: got=%q, want=*%q*", rr.Stdout.Bytes(), want)
+	}
+}
+
 // startHTTPProxy runs a local http proxy and sets the env vars for it.
 func startHTTPProxy(t *testing.T) (*http.Server, error) {
 	port, err := freeport.GetFreePort()