toClose.add(it)
      }
    set("a", "a", "a")
    assertThat(filesystem.exists(dir / "a.0")).isTrue()
    assertThat(filesystem.exists(dir / "a.1")).isTrue()
    assertThat(filesystem.exists(dir / "journal")).isTrue()
  }

  @ParameterizedTest
  @ArgumentsSource(FileSystemParamProvider::class)
  fun fileDeletedExternally(parameters: Pair<FileSystem, Boolean>) {

import assertk.assertions.hasMessage
import assertk.assertions.isCloseTo
import assertk.assertions.isEqualTo
import assertk.assertions.isFalse
import assertk.assertions.isNull
import assertk.assertions.isTrue
import assertk.fail
import java.io.IOException
import java.net.HttpURLConnection
import java.net.SocketTimeoutException
import java.time.Duration
import java.util.Arrays
import java.util.concurrent.BlockingQueue

import assertk.assertions.isCloseTo
import assertk.assertions.isEqualTo
import assertk.assertions.isFalse
import assertk.assertions.isGreaterThan
import assertk.assertions.isLessThan
import assertk.assertions.isTrue
import java.io.EOFException
import java.io.IOException
import java.io.InterruptedIOException
import java.util.concurrent.CountDownLatch
import java.util.concurrent.TimeUnit
import java.util.concurrent.atomic.AtomicInteger