@Override
  public void start() {
    checkState(ceMainThread == null, "start() can not be called twice");
    // start main thread
    ceMainThread = new CeMainThread();
    ceMainThread.start();
  }
@Test
  public void start_starts_a_new_Thread() {
    assertThat(ceThreadExists()).isFalse();
    newCeServer().start();
    assertThat(ceThreadExists()).isTrue();
  }