private static void checkAsyncLock(AsynchronousFileChannel channel) throws Throwable {
    assertNotNull(channel.lock().get());
    assertNotNull(channel.lock(0, 10, true).get());

    SettableFuture<FileLock> future = SettableFuture.create();
    channel.lock(0, 10, true, null, setFuture(future));

    assertNotNull(future.get(10, SECONDS));
  }
Just tests the main read/write methods... the methods all delegate to the non-async channel
anyway.
jimfs/src/test/java/com/google/common/jimfs/JimfsAsynchronousFileChannelTest.java