filesystem.setFaultyDelete(cacheDir / "k1.0.tmp", false)
    filesystem.setFaultyDelete(cacheDir, false)
    val snapshot = cache["k1"]
    assertThat(snapshot).isNull()
  }

  @Test
  fun validateKey() {
    var key = ""
    assertFailsWith<IllegalArgumentException> {
      key = "has_space "
      cache.edit(key)
    }.also { expected ->