@Test
  public void whenNoPendingTransactions() {
    VetoCommitBarrier barrier = new VetoCommitBarrier();
    barrier.vetoCommit();

    assertTrue(barrier.isCommitted());
  }
  @Test
  public void whenBarrierCommitted_thenIgnored() {
    VetoCommitBarrier barrier = new VetoCommitBarrier();
    barrier.vetoCommit();

    barrier.vetoCommit();
    assertTrue(barrier.isCommitted());
  }
  @Test
  public void whenCommitted() throws InterruptedException {
    barrier = new VetoCommitBarrier();
    barrier.atomicVetoCommit();

    barrier.awaitOpen();
    assertTrue(barrier.isCommitted());
  }