@Test
public void testOpen() throws Exception {

  Mutation.Metadata metadata = mock(Mutation.Metadata.class);
  when(firstMutation.getMetadata()).thenReturn(metadata);
  when(metadata.getTimestamp()).thenReturn(0L);
  destination.send(ImmutableList.of(firstMutation));
  assertEquals(firstMutation, destination.getLastPublishedMutation());
  destination.open();
  assertNull(destination.getLastPublishedMutation());
  verify(listener, times(1)).onStart();
}