future.addListener(after, directExecutor());

    future.set(1); // BadRunnableException must not propagate.

    before.assertRun();
    after.assertRun();
  }

  public void testNullListener() {
    assertThrows(NullPointerException.class, () -> future.addListener(null, directExecutor()));
  }

  public void testNullExecutor() {