public long nowInUnixTime() {
    return clock.currentTimeMs() / 1000;
  }
@Test
  public void returnsCurrentUnixTime() {
    // Given
    long expCurrentUnixTime = 12345678L;
    TimeUtils tu = new TimeUtils(new FixedClock(expCurrentUnixTime * 1000));

    // When/Then
    assertEquals(expCurrentUnixTime, tu.nowInUnixTime());
  }