set("b", "b1", "b2")
    val iterator = cache.snapshots()
    iterator.next().use {
      assertThat(it.key()).isEqualTo("a")
    }
    set("b", "b3", "b4")
    iterator.next().use {
      assertThat(it.key()).isEqualTo("b")
      it.assertValue(0, "b3")
      it.assertValue(1, "b4")
    }
  }

  @ParameterizedTest
  @ArgumentsSource(FileSystemParamProvider::class)