Calling PatchAction on typed objects should work correctly

Only Unstructured objects worked (because unstructured implicitly
clears the .Object map when Unmarshal is called). We must reset
obj before we attempt to unmarshal into it.

staging/src/k8s.io/client-go/testing/fixture.go

@@ -18,9 +18,11 @@ package testing
 
 import (
 	"fmt"
+	"reflect"
 	"sync"
 
 	jsonpatch "github.com/evanphx/json-patch"
+
 	"k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -139,6 +141,11 @@ func ObjectReaction(tracker ObjectTracker) ReactionFunc {
 				return true, nil, err
 			}
 
+			// reset the object in preparation to unmarshal, since unmarshal does not guarantee that fields
+			// in obj that are removed by patch are cleared
+			value := reflect.ValueOf(obj)
+			value.Elem().Set(reflect.New(value.Type().Elem()).Elem())
+
 			switch action.GetPatchType() {
 			case types.JSONPatchType:
 				patch, err := jsonpatch.DecodePatch(action.GetPatch())
@@ -149,6 +156,7 @@ func ObjectReaction(tracker ObjectTracker) ReactionFunc {
 				if err != nil {
 					return true, nil, err
 				}
+
 				if err = json.Unmarshal(modified, obj); err != nil {
 					return true, nil, err
 				}