integration/api: check field items in empty List

Signed-off-by: xyz-li <hui0787411@163.com>

test/integration/apimachinery/check_list_fields_test.go

@@ -0,0 +1,99 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package apimachinery
+
+import (
+	"context"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"testing"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/sets"
+	"k8s.io/client-go/dynamic"
+	"k8s.io/client-go/kubernetes"
+	kubeapiservertesting "k8s.io/kubernetes/cmd/kube-apiserver/app/testing"
+	"k8s.io/kubernetes/test/integration/framework"
+)
+
+func TestCheckFieldItemsInEmptyList(t *testing.T) {
+	server := kubeapiservertesting.StartTestServerOrDie(t, nil, []string{
+		"--runtime-config=api/all=true",
+	}, framework.SharedEtcd())
+
+	defer server.TearDownFn()
+
+	clientSet, err := kubernetes.NewForConfig(server.ClientConfig)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dynamicClient, err := dynamic.NewForConfig(server.ClientConfig)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, lists, err := clientSet.Discovery().ServerGroupsAndResources()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, resources := range lists {
+		for _, resource := range resources.APIResources {
+			gv, err := schema.ParseGroupVersion(resources.GroupVersion)
+			if err != nil {
+				t.Fatal(err)
+			}
+			gvr := schema.GroupVersionResource{
+				Group:    gv.Group,
+				Version:  gv.Version,
+				Resource: resource.Name,
+			}
+
+			if !sets.NewString(resource.Verbs...).Has("list") {
+				t.Logf("skip gvr: %s", gvr)
+				continue
+			}
+
+			var list *unstructured.UnstructuredList
+			if resource.Namespaced {
+				list, err = dynamicClient.Resource(gvr).Namespace("non-exist").List(context.Background(),
+					metav1.ListOptions{LabelSelector: "non-exist=non-exist"})
+			} else {
+				list, err = dynamicClient.Resource(gvr).List(context.Background(),
+					metav1.ListOptions{LabelSelector: "non-exist=non-exist"})
+			}
+
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if list == nil {
+				t.Fatalf("gvr: %s, list is nil", gvr)
+			}
+
+			// Field `items` in List object should be a zero-length array when no obj in etcd.
+			if list.Items == nil {
+				t.Fatalf("gvr: %s, fields items of list is nil", gvr)
+			}
+
+			if len(list.Items) > 0 {
+				t.Fatalf("gvr: %s, fields items should be a zero-length array", gvr)
+			}
+		}
+	}
+}