}
    assertThat(iterator.hasNext()).isFalse()
    assertFailsWith<NoSuchElementException> {
      iterator.next()
    }
  }

  @Test
  fun iteratorElementsAddedDuringIterationAreOmitted() {
    set("a", "a1", "a2")
    set("b", "b1", "b2")
    val iterator = cache.snapshots()
    iterator.next().use { a ->
      assertThat(a.key()).isEqualTo("a")
    }