Fakeclient: Allow Update with empty ResourceVersion

pkg/client/fake/client.go

@@ -118,6 +118,11 @@ func (t versionedTracker) Update(gvr schema.GroupVersionResource, obj runtime.Ob
 	if err != nil {
 		return err
 	}
+
+	// If the new object does not have the resource version set, default it to the resource version of the existing resource
+	if accessor.GetResourceVersion() == "" {
+		accessor.SetResourceVersion(oldAccessor.GetResourceVersion())
+	}
 	if accessor.GetResourceVersion() != oldAccessor.GetResourceVersion() {
 		return apierrors.NewConflict(gvr.GroupResource(), accessor.GetName(), errors.New("object was modified"))
 	}

pkg/client/fake/client_test.go

@@ -276,6 +276,36 @@ var _ = Describe("Fake client", func() {
 			Expect(obj.ObjectMeta.ResourceVersion).To(Equal("1"))
 		})
 
+		It("should allow updates with non-set ResourceVersion", func() {
+			By("Updating a new configmap")
+			newcm := &corev1.ConfigMap{
+				TypeMeta: metav1.TypeMeta{
+					APIVersion: "v1",
+					Kind:       "ConfigMap",
+				},
+				ObjectMeta: metav1.ObjectMeta{
+					Name:            "test-cm",
+					Namespace:       "ns2",
+				},
+				Data: map[string]string{
+					"test-key": "new-value",
+				},
+			}
+			err := cl.Update(context.Background(), newcm)
+			Expect(err).To(BeNil())
+
+			By("Getting the configmap")
+			namespacedName := types.NamespacedName{
+				Name:      "test-cm",
+				Namespace: "ns2",
+			}
+			obj := &corev1.ConfigMap{}
+			err = cl.Get(context.Background(), namespacedName, obj)
+			Expect(err).To(BeNil())
+			Expect(obj).To(Equal(newcm))
+			Expect(obj.ObjectMeta.ResourceVersion).To(Equal("1"))
+		})
+
 		It("should reject updates with non-matching ResourceVersion", func() {
 			By("Updating a new configmap")
 			newcm := &corev1.ConfigMap{