@Test
public void testClose() throws Exception {

  doNothing().when(mockBulkMutation).sendUnsent();
  doNothing().when(mockBulkMutation).flush();
  doNothing().when(mockBulkMutation).close();
  asyncBufferedMutator.close();
  verify(mockBulkMutation).sendUnsent();
  verify(mockBulkMutation).flush();
  verify(mockBulkMutation).close();
}