@Test
public void testEmptyHistory() throws Exception {

  MysqlSourceState state = mock(MysqlSourceState.class);
  TestRepository repository = new TestRepository();
  StateHistory<MysqlSourceState> history =
      new StateHistory<>(SOURCE_NAME, 2, repository, metrics);
  assertTrue(history.isEmpty());
  repository = new TestRepository(state);
  history = new StateHistory<>(SOURCE_NAME, 2, repository, metrics);
  assertFalse(history.isEmpty());
}