// incomplete.
    val creator = cache.edit("k1")!!
    creator.newSink(0).buffer().use {
      it.writeUtf8("Hello")
    }

    // Simulate a severe Filesystem failure on the first initialization.
    filesystem.setFaultyDelete(cacheDir / "k1.0.tmp", true)
    filesystem.setFaultyDelete(cacheDir, true)
    cache =