fun cacheClosedTruncatesIterator() {
    set("a", "a1", "a2")
    val iterator = cache.snapshots()
    cache.close()
    assertThat(iterator.hasNext()).isFalse()
  }

  @Test
  fun isClosed_uninitializedCache() {
    // Create an uninitialized cache.
    cache =
      DiskLruCache(filesystem, cacheDir, appVersion, 2, Int.MAX_VALUE.toLong(), taskRunner).also {
        toClose.add(it)
      }