demonstrate existing generated client and fake client behavior is consistent

staging/src/k8s.io/client-go/kubernetes_test/BUILD

@@ -2,11 +2,18 @@ load("@io_bazel_rules_go//go:def.bzl", "go_test")
 
 go_test(
     name = "go_default_test",
-    srcs = ["timeout_test.go"],
+    srcs = [
+        "fake_client_test.go",
+        "timeout_test.go",
+    ],
     deps = [
         "//staging/src/k8s.io/api/apps/v1:go_default_library",
+        "//staging/src/k8s.io/api/core/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
         "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
+        "//staging/src/k8s.io/client-go/kubernetes/fake:go_default_library",
         "//staging/src/k8s.io/client-go/kubernetes/scheme:go_default_library",
         "//staging/src/k8s.io/client-go/rest:go_default_library",
         "//staging/src/k8s.io/client-go/rest/fake:go_default_library",

staging/src/k8s.io/client-go/kubernetes_test/fake_client_test.go

@@ -0,0 +1,93 @@
+/*
+Copyright 2020 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 kubernetes
+
+import (
+	"context"
+	"testing"
+
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/client-go/kubernetes/fake"
+	"k8s.io/client-go/kubernetes/scheme"
+)
+
+// This test proves that the kube fake client does not return GVKs.  This is consistent with actual client (see tests below)
+// and should not be changed unless the decoding behavior and somehow literal creation (`&corev1.ConfigMap{}`) behavior change.
+func Test_ConfigMapFakeClient(t *testing.T) {
+	fakeKubeClient := fake.NewSimpleClientset(&corev1.ConfigMap{ObjectMeta: metav1.ObjectMeta{Namespace: "foo-ns", Name: "foo-name"}})
+	cm, err := fakeKubeClient.CoreV1().ConfigMaps("foo-ns").Get(context.TODO(), "foo-name", metav1.GetOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if cm.GetObjectKind().GroupVersionKind() != (schema.GroupVersionKind{}) {
+		t.Fatal(cm.GetObjectKind().GroupVersionKind())
+	}
+	cmList, err := fakeKubeClient.CoreV1().ConfigMaps("foo-ns").List(context.TODO(), metav1.ListOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if cmList.GetObjectKind().GroupVersionKind() != (schema.GroupVersionKind{}) {
+		t.Fatal(cmList.GetObjectKind().GroupVersionKind())
+	}
+}
+
+// This test checks decoding behavior for the actual client to ensure the fake client (tested above) is consistent.
+func TestGetDecoding(t *testing.T) {
+	// this the duplication of logic from the real Get API for configmaps.  This will prove that the generated client will not return a GVK
+	mediaTypes := scheme.Codecs.WithoutConversion().SupportedMediaTypes()
+	info, ok := runtime.SerializerInfoForMediaType(mediaTypes, "application/json")
+	if !ok {
+		t.Fatal("missing serializer")
+	}
+	decoder := scheme.Codecs.WithoutConversion().DecoderToVersion(info.Serializer, corev1.SchemeGroupVersion)
+
+	body := []byte(`{"apiVersion": "v1", "kind": "ConfigMap", "metadata":{"Namespace":"foo","Name":"bar"}}`)
+	obj := &corev1.ConfigMap{}
+	out, _, err := decoder.Decode(body, nil, obj)
+	if err != nil || out != obj {
+		t.Fatal(err)
+	}
+
+	if obj.GetObjectKind().GroupVersionKind() != (schema.GroupVersionKind{}) {
+		t.Fatal(obj.GetObjectKind().GroupVersionKind())
+	}
+}
+
+// This test checks decoding behavior for the actual client to ensure the fake client (tested above) is consistent.
+func TestListDecoding(t *testing.T) {
+	// this the duplication of logic from the real Get API for configmaps.  This will prove that the generated client will not return a GVK
+	mediaTypes := scheme.Codecs.WithoutConversion().SupportedMediaTypes()
+	info, ok := runtime.SerializerInfoForMediaType(mediaTypes, "application/json")
+	if !ok {
+		t.Fatal("missing serializer")
+	}
+	decoder := scheme.Codecs.WithoutConversion().DecoderToVersion(info.Serializer, corev1.SchemeGroupVersion)
+
+	body := []byte(`{"apiVersion": "v1", "kind": "ConfigMapList", "items":[]}`)
+	obj := &corev1.ConfigMapList{}
+	out, _, err := decoder.Decode(body, nil, obj)
+	if err != nil || out != obj {
+		t.Fatal(err)
+	}
+
+	if obj.GetObjectKind().GroupVersionKind() != (schema.GroupVersionKind{}) {
+		t.Fatal(obj.GetObjectKind().GroupVersionKind())
+	}
+}