Merge pull request kubernetes#77681 from soltysh/fix_get

Fix handling empty result when invoking kubectl get

pkg/kubectl/cmd/get/get.go

@@ -750,8 +750,8 @@ func (o *GetOptions) printGeneric(r *resource.Result) error {
 	}
 
 	var obj runtime.Object
-	if !singleItemImplied || len(infos) > 1 {
-		// we have more than one item, so coerce all items into a list.
+	if !singleItemImplied || len(infos) != 1 {
+		// we have zero or multple items, so coerce all items into a list.
 		// we don't want an *unstructured.Unstructured list yet, as we
 		// may be dealing with non-unstructured objects. Compose all items
 		// into an corev1.List, and then decode using an unstructured scheme.

pkg/kubectl/cmd/get/get_test.go

@@ -702,6 +702,60 @@ func TestGetObjectIgnoreNotFound(t *testing.T) {
 	}
 }
 
+func TestEmptyResult(t *testing.T) {
+	cmdtesting.InitTestErrorHandler(t)
+
+	tf := cmdtesting.NewTestFactory().WithNamespace("test")
+	defer tf.Cleanup()
+	codec := scheme.Codecs.LegacyCodec(scheme.Scheme.PrioritizedVersionsAllGroups()...)
+
+	tf.UnstructuredClient = &fake.RESTClient{
+		NegotiatedSerializer: resource.UnstructuredPlusDefaultContentConfig().NegotiatedSerializer,
+		Client: fake.CreateHTTPClient(func(req *http.Request) (*http.Response, error) {
+			return &http.Response{StatusCode: 200, Header: cmdtesting.DefaultHeader(), Body: cmdtesting.ObjBody(codec, &corev1.PodList{})}, nil
+		}),
+	}
+
+	streams, _, _, errbuf := genericclioptions.NewTestIOStreams()
+	cmd := NewCmdGet("kubectl", tf, streams)
+	// we're assuming that an empty file is being passed from stdin
+	cmd.Flags().Set("filename", "-")
+	cmd.Run(cmd, []string{})
+
+	if !strings.Contains(errbuf.String(), "No resources found") {
+		t.Errorf("unexpected output: %q", errbuf.String())
+	}
+}
+
+func TestEmptyResultJSON(t *testing.T) {
+	cmdtesting.InitTestErrorHandler(t)
+
+	tf := cmdtesting.NewTestFactory().WithNamespace("test")
+	defer tf.Cleanup()
+	codec := scheme.Codecs.LegacyCodec(scheme.Scheme.PrioritizedVersionsAllGroups()...)
+
+	tf.UnstructuredClient = &fake.RESTClient{
+		NegotiatedSerializer: resource.UnstructuredPlusDefaultContentConfig().NegotiatedSerializer,
+		Client: fake.CreateHTTPClient(func(req *http.Request) (*http.Response, error) {
+			return &http.Response{StatusCode: 200, Header: cmdtesting.DefaultHeader(), Body: cmdtesting.ObjBody(codec, &corev1.PodList{})}, nil
+		}),
+	}
+
+	streams, _, outbuf, errbuf := genericclioptions.NewTestIOStreams()
+	cmd := NewCmdGet("kubectl", tf, streams)
+	// we're assuming that an empty file is being passed from stdin
+	cmd.Flags().Set("filename", "-")
+	cmd.Flags().Set("output", "json")
+	cmd.Run(cmd, []string{})
+
+	if errbuf.Len() > 0 {
+		t.Errorf("unexpected error: %q", errbuf.String())
+	}
+	if !strings.Contains(outbuf.String(), `"items": []`) {
+		t.Errorf("unexpected output: %q", outbuf.String())
+	}
+}
+
 func TestGetSortedObjects(t *testing.T) {
 	pods := &corev1.PodList{
 		ListMeta: metav1.ListMeta{