for (LoadingCache<Object, Object> cache : caches()) {
      checkEmpty(cache);
    }
  }


  public void testInvalidate_empty() {
    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked("a");
      cache.getUnchecked("b");
      cache.invalidate("a");
      cache.invalidate("b");
      cache.invalidate(0);
      checkEmpty(cache);
    }
  }

  public void testInvalidateAll_empty() {

        assertThat(keys.remove(key)).isTrue();
        assertThat(keys.remove(key)).isFalse();
        assertThat(keys.contains(key)).isFalse();
      }
      checkEmpty(keys);
      checkEmpty(cache);
    }
  }

  public void testValues_populated() {
    for (LoadingCache<Object, Object> cache : caches()) {
      Collection<Object> values = cache.asMap().values();

    }
  }

  public void testEmpty() throws Exception {
    for (BlockingQueue<Object> q : blockingQueues()) {
      checkEmpty(q);
    }
  }

  private void checkEmpty(BlockingQueue<Object> q) {
    assertDrained(q);
  }

  public void testNegativeMaxElements() throws Exception {
    for (BlockingQueue<Object> q : blockingQueues()) {

    Object key = new Object();
    assertThat(nullCache.getUnchecked(key)).isSameInstanceAs(key);
    assertThat(listener.getCount()).isEqualTo(1);
    assertThat(nullCache.size()).isEqualTo(0);
    CacheTesting.checkEmpty(nullCache.asMap());
  }

  @J2ktIncompatible
  @GwtIncompatible // QueuingRemovalListener
  public void testRemovalNotification_clear() throws InterruptedException {

    Object key = new Object();
    assertThat(nullCache.getUnchecked(key)).isSameInstanceAs(key);
    assertThat(listener.getCount()).isEqualTo(1);
    assertThat(nullCache.size()).isEqualTo(0);
    CacheTesting.checkEmpty(nullCache.asMap());
  }

  @J2ktIncompatible
  @GwtIncompatible // QueuingRemovalListener
  public void testRemovalNotification_clear() throws InterruptedException {