address comments

staging/src/k8s.io/cli-runtime/pkg/genericclioptions/resource/builder.go

@@ -140,7 +140,7 @@ func (o *FilenameOptions) validate() []error {
 		errs = append(errs, fmt.Errorf("only one of -f or -k can be specified"))
 	}
 	if len(o.Kustomize) > 0 && o.Recursive {
-		errs = append(errs, fmt.Errorf("-R is not allowed to work with -k"))
+		errs = append(errs, fmt.Errorf("the -k flag can't be used with -f or -R"))
 	}
 	return errs
 }

staging/src/k8s.io/cli-runtime/pkg/genericclioptions/resource/builder_test.go

@@ -392,7 +392,7 @@ func TestFilenameOptionsValidate(t *testing.T) {
 			kustomize: "dir",
 			recursive: true,
 			errExp:    true,
-			msgExp:    "-R is not allowed to work with -k",
+			msgExp:    "the -k flag can't be used with -f or -R",
 		},
 		{
 			filenames: []string{"file"},
@@ -673,6 +673,11 @@ func TestKustomizeDirectoryBuilder(t *testing.T) {
 			expectErr:     false,
 			expectedNames: []string{"test-the-map", "test-the-deployment", "test-the-service"},
 		},
+		{
+			directory: filepath.Join(dir, "kustomization.yaml"),
+			expectErr: true,
+			errMsg:    "must be a directory to be a root",
+		},
 		{
 			directory: "../../../artifacts/kustomization/should-not-load.yaml",
 			expectErr: true,

test/cmd/apply.sh

@@ -229,7 +229,7 @@ __EOF__
   kube::test::get_object_assert 'deployment test-the-deployment' "{{${id_field}}}" 'test-the-deployment'
   kube::test::get_object_assert 'service test-the-service' "{{${id_field}}}" 'test-the-service'
   # cleanup
-  kubectl delete configmap/test-the-map deployment/test-the-deployment service/test-the-service
+  kubectl delete -k hack/testdata/kustomize
 
   ## kubectl apply --kustomize somedir
   kubectl apply --kustomize hack/testdata/kustomize
@@ -237,7 +237,7 @@ __EOF__
   kube::test::get_object_assert 'deployment test-the-deployment' "{{${id_field}}}" 'test-the-deployment'
   kube::test::get_object_assert 'service test-the-service' "{{${id_field}}}" 'test-the-service'
   # cleanup
-  kubectl delete -k hack/testdata/kustomize
+  kubectl delete --kustomize hack/testdata/kustomize
 
   set +o nounset
   set +o errexit