tests/types: fix test case TestUnmarshalToReusedObject

- Add check for when an object is empty and unmarshalles JSON
  to be equal with the reused object.

tests/types/types_test.go

@@ -169,14 +169,23 @@ func TestUnmarshalToReusedObject(t *testing.T) {
 	var record ff.Everything
 	err := record.UnmarshalJSON([]byte(JSONWhole))
 	if err != nil {
-		t.Errorf("%v", err)
+		t.Errorf("UnmarshalJSON: %v", err)
 	}
 
 	for _, part := range JSONParts {
 		reuseRecord := record
 		reuseRecord.UnmarshalJSON([]byte("{" + part + "}"))
 		if reflect.DeepEqual(record, reuseRecord) {
-			t.Errorf("%v should not be equal to %v\nrecord = %v\nreuseRecord = %v", JSONWhole, part, record, reuseRecord)
+			t.Fatalf("UnmarshalJSON: %v", err)
+		}
+
+		var emptyRecord ff.Everything
+		if err := emptyRecord.UnmarshalJSON([]byte("{" + part + "}")); err != nil {
+			t.Fatalf("UnmarshalJSON: %v", err)
+		}
+
+		if !reflect.DeepEqual(reuseRecord, emptyRecord) {
+			t.Errorf("%#v should be equal to %#v", reuseRecord, emptyRecord)
 		}
 	}
 }