@Override
  public void startup() {
    checkState(this.status == Status.INIT, "startup() can not be called multiple times");
    try {
      this.status = Status.STARTING;
      this.computeEngineContainer.start(props);
    } finally {
      this.status = Status.STARTED;
    }
  }
@Test
  public void startup_throws_ISE_when_called_twice() {
    underTest.startup();

    assertThatThrownBy(underTest::startup)
      .isInstanceOf(IllegalStateException.class)
      .hasMessage("startup() can not be called multiple times");
  }