tasks.remove().run();
    }

    void runAll() {
      while (hasNext()) {
        runNext();
      }
    }
  }

  private FakeExecutor fakePool;
  private SequentialExecutor e;

  @Override
  public void setUp() {
    fakePool = new FakeExecutor();
    e = new SequentialExecutor(fakePool);
  }

  public void testConstructingWithNullExecutor_fails() {