Merge pull request #50329 from rrati/raw-unmarshal-nil

Automatic merge from submit-queue (batch tested with PRs 47034, 50329)

RawExtension unmarshal will produce empty objects if the original object was nil #50323

**What this PR does / why we need it**:
marshaled nil objects will be unmarshaled as nil objects instead of a byte array "null", which better represents the original object before marshaling

fixes #50323

@kubernetes/sig-api-machinery-bugs

staging/src/k8s.io/apimachinery/pkg/runtime/embedded_test.go

@@ -197,8 +197,8 @@ func TestNestedObject(t *testing.T) {
 	if externalViaJSON.Kind == "" || externalViaJSON.APIVersion == "" || externalViaJSON.ID != "outer" {
 		t.Errorf("Expected objects to have type info set, got %#v", externalViaJSON)
 	}
-	if !reflect.DeepEqual(externalViaJSON.EmptyObject.Raw, []byte("null")) || len(externalViaJSON.Object.Raw) == 0 {
-		t.Errorf("Expected deserialization of nested objects into bytes, got %#v", externalViaJSON)
+	if len(externalViaJSON.EmptyObject.Raw) > 0 {
+		t.Errorf("Expected deserialization of empty nested objects into empty bytes, got %#v", externalViaJSON)
 	}
 
 	// test JSON decoding, too, since Decode uses yaml unmarshalling.

staging/src/k8s.io/apimachinery/pkg/runtime/extension.go

@@ -17,6 +17,7 @@ limitations under the License.
 package runtime
 
 import (
+	"bytes"
 	"encoding/json"
 	"errors"
 )
@@ -25,7 +26,9 @@ func (re *RawExtension) UnmarshalJSON(in []byte) error {
 	if re == nil {
 		return errors.New("runtime.RawExtension: UnmarshalJSON on nil pointer")
 	}
-	re.Raw = append(re.Raw[0:0], in...)
+	if !bytes.Equal(in, []byte("null")) {
+		re.Raw = append(re.Raw[0:0], in...)
+	}
 	return nil
 }
 

staging/src/k8s.io/apimachinery/pkg/runtime/extension_test.go

@@ -17,7 +17,9 @@ limitations under the License.
 package runtime_test
 
 import (
+	"bytes"
 	"encoding/json"
+	"reflect"
 	"testing"
 
 	"k8s.io/apimachinery/pkg/runtime"
@@ -37,3 +39,75 @@ func TestEmbeddedRawExtensionMarshal(t *testing.T) {
 		t.Errorf("unexpected data: %s", string(data))
 	}
 }
+func TestEmbeddedRawExtensionUnmarshal(t *testing.T) {
+	type test struct {
+		Ext runtime.RawExtension
+	}
+
+	testCases := map[string]struct {
+		orig test
+	}{
+		"non-empty object": {
+			orig: test{Ext: runtime.RawExtension{Raw: []byte(`{"foo":"bar"}`)}},
+		},
+		"empty object": {
+			orig: test{Ext: runtime.RawExtension{}},
+		},
+	}
+
+	for k, tc := range testCases {
+		new := test{}
+		data, _ := json.Marshal(tc.orig)
+		if err := json.Unmarshal(data, &new); err != nil {
+			t.Errorf("%s: umarshal error: %v", k, err)
+		}
+		if !reflect.DeepEqual(tc.orig, new) {
+			t.Errorf("%s: unmarshaled struct differs from original: %v %v", k, tc.orig, new)
+		}
+	}
+}
+
+func TestEmbeddedRawExtensionRoundTrip(t *testing.T) {
+	type test struct {
+		Ext runtime.RawExtension
+	}
+
+	testCases := map[string]struct {
+		orig test
+	}{
+		"non-empty object": {
+			orig: test{Ext: runtime.RawExtension{Raw: []byte(`{"foo":"bar"}`)}},
+		},
+		"empty object": {
+			orig: test{Ext: runtime.RawExtension{}},
+		},
+	}
+
+	for k, tc := range testCases {
+		new1 := test{}
+		new2 := test{}
+		data, err := json.Marshal(tc.orig)
+		if err != nil {
+			t.Errorf("1st marshal error: %v", err)
+		}
+		if err = json.Unmarshal(data, &new1); err != nil {
+			t.Errorf("1st unmarshal error: %v", err)
+		}
+		newData, err := json.Marshal(new1)
+		if err != nil {
+			t.Errorf("2st marshal error: %v", err)
+		}
+		if err = json.Unmarshal(newData, &new2); err != nil {
+			t.Errorf("2nd unmarshal error: %v", err)
+		}
+		if !bytes.Equal(data, newData) {
+			t.Errorf("%s: re-marshaled data differs from original: %v %v", k, data, newData)
+		}
+		if !reflect.DeepEqual(tc.orig, new1) {
+			t.Errorf("%s: unmarshaled struct differs from original: %v %v", k, tc.orig, new1)
+		}
+		if !reflect.DeepEqual(new1, new2) {
+			t.Errorf("%s: re-unmarshaled struct differs from original: %v %v", k, new1, new2)
+		}
+	}
+}