val snapshot = cache["k1"]
    assertThat(snapshot).isNull()
  }

  @Test
  fun validateKey() {
    var key = ""
    assertFailsWith<IllegalArgumentException> {
      key = "has_space "
      cache.edit(key)
    }.also { expected ->
      assertThat(expected.message).isEqualTo("keys must match regex [a-z0-9_-]{1,120}: \"$key\"")
    }
    assertFailsWith<IllegalArgumentException> {