bug: Fix status subresource getting updated on Update when it is empty

Before this, Update and Patch requests will override to-level status fields for objects that have a status resource if the status was initially empty. This happens because the code to set the status to what we already have in the unupdated object converts the object into a `map[string]any` using json serialization/deserialization, copies the original `status` field, then converts back. The json deserializer unfortunatelly does not properly clear the target, allowing data to remain that is absent in the json serialization.

Author: alvaroaleman

pkg/client/fake/client.go

@@ -995,6 +995,7 @@ func fromMapStringAny(u map[string]any, target runtime.Object) error {
 return fmt.Errorf("failed to serialize: %w", err)
 }
 
+zero(target)
 if err := json.Unmarshal(serialized, &target); err != nil {
 return fmt.Errorf("failed to deserialize: %w", err)
 }

pkg/client/fake/client_test.go

@@ -1409,22 +1409,19 @@ var _ = Describe("Fake client", func() {
 })
 
 It("should not change the status of typed objects that have a status subresource on update", func() {
-obj := &corev1.Node{
+obj := &corev1.Pod{
 ObjectMeta: metav1.ObjectMeta{
-Name: "node",
-},
-Status: corev1.NodeStatus{
-NodeInfo: corev1.NodeSystemInfo{MachineID: "machine-id"},
+Name: "pod",
 },
 }
 cl := NewClientBuilder().WithStatusSubresource(obj).WithObjects(obj).Build()
 
-obj.Status.NodeInfo.MachineID = "updated-machine-id"
+obj.Status.Phase = "Running"
 Expect(cl.Update(context.Background(), obj)).To(Succeed())
 
 Expect(cl.Get(context.Background(), client.ObjectKeyFromObject(obj), obj)).To(Succeed())
 
-Expect(obj.Status).To(BeEquivalentTo(corev1.NodeStatus{NodeInfo: corev1.NodeSystemInfo{MachineID: "machine-id"}}))
+Expect(obj.Status).To(BeEquivalentTo(corev1.PodStatus{}))
 })
 
 It("should return a conflict error when an incorrect RV is used on status update", func() {
@@ -1511,25 +1508,20 @@ var _ = Describe("Fake client", func() {
 })
 
 It("should not change the status of typed objects that have a status subresource on patch", func() {
-obj := &corev1.Node{
+obj := &corev1.Pod{
 ObjectMeta: metav1.ObjectMeta{
 Name: "node",
 },
-Status: corev1.NodeStatus{
-NodeInfo: corev1.NodeSystemInfo{
-MachineID: "machine-id",
-},
-},
 }
 Expect(cl.Create(context.Background(), obj)).To(Succeed())
 original := obj.DeepCopy()
 
-obj.Status.NodeInfo.MachineID = "machine-id-from-patch"
+obj.Status.Phase = "Running"
 Expect(cl.Patch(context.Background(), obj, client.MergeFrom(original))).To(Succeed())
 
 Expect(cl.Get(context.Background(), client.ObjectKeyFromObject(obj), obj)).To(Succeed())
 
-Expect(obj.Status).To(BeEquivalentTo(corev1.NodeStatus{NodeInfo: corev1.NodeSystemInfo{MachineID: "machine-id"}}))
+Expect(obj.Status).To(BeEquivalentTo(corev1.PodStatus{}))
 })
 
 It("should not change non-status field of typed objects that have a status subresource on status patch", func() {