private void testProcess(IFrameTupleAccessor accessor) throws HyracksDataException {
   IFrameWriter writer = prepareValidator(accessor);
   writer.open();
   for (int tid = 0; tid < accessor.getTupleCount(); tid++) {
     for (int fid = 0; fid < fields.length; fid++) {
       if (!appender.appendField(accessor, tid, fid)) {
         appender.flush(writer, true);
         if (!appender.appendField(accessor, tid, fid)) {}
       }
     }
   }
   appender.flush(writer, true);
   writer.close();
 }
 @Before
 public void createAppender() throws HyracksDataException {
   appender = new FrameFixedFieldAppender(fields.length);
   FrameManager manager = new FrameManager(TEST_FRAME_SIZE);
   IFrame frame = new VSizeFrame(manager);
   appender.reset(frame, true);
 }
 @Test
 public void testResetShouldWork() throws HyracksDataException {
   testAppendFieldShouldSucceed();
   appender.reset(new VSizeFrame(new FrameManager(TEST_FRAME_SIZE)), true);
   testAppendFieldShouldSucceed();
 }