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.isEqualTo
import assertk.assertions.isFalse
import assertk.assertions.isGreaterThan
import assertk.assertions.isLessThan
import assertk.assertions.isNull
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

        .that(step2.statusFuture().isCancelled())
        .isTrue();
    // Its closeable is closed.
    assertClosed(closeable2);

    // Step 3 was cancelled before it began
    assertWithMessage("step3.statusFuture().isCancelled()")
        .that(step3.statusFuture().isCancelled())
        .isTrue();
    // Its closeable is still open.
    assertStillOpen(closeable3);

        .containsNoneOf(Object.class, new TypeToken<Iterable<Number>>() {}.getType());
    assertThat(new TypeToken<List<? extends Number>>() {}.isSupertypeOf(fieldType)).isTrue();
    assertThat(new TypeToken<List<? extends Iterable<?>>>() {}.isSupertypeOf(fieldType)).isTrue();
    assertThat(new TypeToken<List<? extends Iterable<Number>>>() {}.isSupertypeOf(fieldType))
        .isFalse();
  }

  public void testArrayClassPreserved() {

        .containsNoneOf(Object.class, new TypeToken<Iterable<Number>>() {}.getType());
    assertThat(new TypeToken<List<? extends Number>>() {}.isSupertypeOf(fieldType)).isTrue();
    assertThat(new TypeToken<List<? extends Iterable<?>>>() {}.isSupertypeOf(fieldType)).isTrue();
    assertThat(new TypeToken<List<? extends Iterable<Number>>>() {}.isSupertypeOf(fieldType))
        .isFalse();
  }

  public void testArrayClassPreserved() {

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