Add CBOR decoder unit test that accepts tag 55799.

Tag 55799 (self-described CBOR) imparts no special semantics on the item it encloses. The CBOR
encoder always encloses its output in this tag so that the prefix 0xd9d9f7 can be used to
mechanically distinguish encoded CBOR from encoded JSON, and the decoder must be able to accept any
sequence of bytes that the encoder can produce.

Author: benluddy

staging/src/k8s.io/apimachinery/pkg/runtime/serializer/cbor/cbor_test.go

@@ -181,6 +181,24 @@ func TestDecode(t *testing.T) {
 		expectedGVK   *schema.GroupVersionKind
 		assertOnError func(*testing.T, error)
 	}{
+		{
+			name:        "self-described cbor tag accepted",
+			data:        []byte("\xd9\xd9\xf7\xa3\x4aapiVersion\x41v\x44kind\x41k\x48metadata\xa1\x44name\x43foo"), // 55799({'apiVersion': 'v', 'kind': 'k', 'metadata': {'name': 'foo'}})
+			gvk:         &schema.GroupVersionKind{},
+			metaFactory: &defaultMetaFactory{},
+			typer:       stubTyper{gvks: []schema.GroupVersionKind{{Version: "v", Kind: "k"}}},
+			into:        &metav1.PartialObjectMetadata{},
+			expectedObj: &metav1.PartialObjectMetadata{
+				TypeMeta:   metav1.TypeMeta{APIVersion: "v", Kind: "k"},
+				ObjectMeta: metav1.ObjectMeta{Name: "foo"},
+			},
+			expectedGVK: &schema.GroupVersionKind{Version: "v", Kind: "k"},
+			assertOnError: func(t *testing.T, err error) {
+				if err != nil {
+					t.Errorf("expected nil error, got: %v", err)
+				}
+			},
+		},
 		{
 			name:        "error determining gvk",
 			metaFactory: stubMetaFactory{err: errors.New("test")},