getAll(cache, asList(6, 8));
    CacheTesting.drainRecencyQueues(cache);
    ticker.advance(1, MILLISECONDS);
    assertThat(keySet).containsExactly(1, 3, 6, 8);

    // get fails to save 1, put saves 3
    cache.asMap().put(3, -3);
    getAll(cache, asList(1));
    CacheTesting.drainRecencyQueues(cache);
    ticker.advance(1, MILLISECONDS);
    assertThat(keySet).containsExactly(6, 8, 3);

  }

  public void testComputeIfPresent() {
    cache.put(key, "1");
    // simultaneous update for same key, expect count successful updates
    doParallelCacheOp(
        count,
        n -> {
          cache.asMap().computeIfPresent(key, (k, v) -> v + delimiter + n);
        });
    assertEquals(1, cache.size());
    assertThat(cache.getIfPresent(key).split(delimiter)).hasLength(count + 1);
  }

public enum RemovalCause {
  /**
   * The entry was manually removed by the user. This can result from the user invoking {@link
   * Cache#invalidate}, {@link Cache#invalidateAll(Iterable)}, {@link Cache#invalidateAll()}, {@link
   * Map#remove}, {@link ConcurrentMap#remove}, or {@link Iterator#remove}.
   */
  EXPLICIT {
    @Override
    boolean wasEvicted() {
      return false;
    }
  },

  /**

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

  /**
   * With an unlimited-size cache with maxWeight of 0, entries weighing 0 should still be cached.
   * Entries with positive weight should not be cached (nor dump existing cache).
   */

        assertTrue(cache.asMap().remove(key, value));
        assertFalse(cache.asMap().remove(key, -1));
        assertFalse(cache.asMap().containsKey(key));
      }
      checkEmpty(cache);
    }
  }


  public void testKeySet_populated() {
    for (LoadingCache<Object, Object> cache : caches()) {
      Set<Object> keys = cache.asMap().keySet();

/**
 * Statistics about the performance of a {@link Cache}. Instances of this class are immutable.
 *
 * <p>Cache statistics are incremented according to the following rules:
 *
 * <ul>
 *   <li>When a cache lookup encounters an existing cache entry {@code hitCount} is incremented.
 *   <li>When a cache lookup first encounters a missing cache entry, a new entry is loaded.
 *       <ul>

/**
 * Statistics about the performance of a {@link Cache}. Instances of this class are immutable.
 *
 * <p>Cache statistics are incremented according to the following rules:
 *
 * <ul>
 *   <li>When a cache lookup encounters an existing cache entry {@code hitCount} is incremented.
 *   <li>When a cache lookup first encounters a missing cache entry, a new entry is loaded.
 *       <ul>

                  }
                });

    // To start, fill up the cache.
    // Each miss both increments the counter and causes the map to grow by one,
    // so until evictions begin, the size of the map is the greatest return
    // value seen so far
    while (cache.getUnchecked(nextRandomKey()) < maximumSize) {}

    requests.set(0);
    misses.set(0);
  }

  @Benchmark
  int time(int reps) {

  }

  public void testGetAllPresent_empty() {
    Cache<Object, Object> cache =
        new AbstractCache<Object, Object>() {
          @Override
          public @Nullable Object getIfPresent(Object key) {
            return null;
          }
        };

    assertEquals(ImmutableMap.of(), cache.getAllPresent(ImmutableList.of(new Object())));
  }

      cache.invalidate("a");
      cache.invalidate("b");
      cache.invalidate(0);
      checkEmpty(cache);
    }
  }

  public void testInvalidateAll_empty() {
    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked("a");
      cache.getUnchecked("b");
      cache.getUnchecked("c");
      cache.invalidateAll();
      checkEmpty(cache);
    }
  }


  public void testEquals_null() {