public void Check_copy_async()
{
var ms = PrepareSourceStream();
var tested = new NarrowedStream(ms, 0, ms.Length - 1);
var reader = new StreamReader(tested);
var result = new MemoryStream();
tested.CopyToAsync(result).Wait();
Assert.Equal(500000*6, result.Length);
}
public static Task CopyToAsync(this Stream self, Stream destination, long from, long to)
{
var limitedStream = new NarrowedStream(self, from, to);
return limitedStream.CopyToAsync(destination, StorageConstants.MaxPageSize);
}