assertThat(cache.asMap().keySet()).isEmpty();

    CacheTesting.processPendingNotifications(cache);
    assertThat(removalListener.getCount()).isEqualTo(1);

    // 2 will be cached
    assertThat(cache.getUnchecked(2)).isEqualTo(2);
    assertThat(cache.asMap().keySet()).containsExactly(2);

    CacheTesting.processPendingNotifications(cache);
    CacheTesting.checkValidState(cache);

        // Fill up heap so soft references get cleared.
        filler = new byte[max(filler.length, filler.length * 2)];
      } catch (OutOfMemoryError e) {
      }
    }

    CacheTesting.processPendingNotifications(cache);
    assertEquals(1, cache.size());
    assertEquals(1, removalListener.getCount());
  }

  // A simple type whose .toString() will return the same value each time, but without maintaining

   * eligibility for garbage collection. This should be called every time expireEntries or
   * evictEntry is called (once the lock is released).
   */
  void processPendingNotifications() {
    RemovalNotification<K, V> notification;
    while ((notification = removalNotificationQueue.poll()) != null) {
      try {
        removalListener.onRemoval(notification);