Async / Await Gotchas

Spot the bug:

    internal Task<DataFormat> TestAsync()
    {
        using (var stream = File.Open("test.dat", FileMode.Open, FileAccess.Read, FileShare.Read))
        {
            return StreamProcessingUtil.DoSomethingAsync(stream);
        }
    }

Oops! We actually need to await the method that gets passed the stream, as without an await, the closing of the using will be hit, disposing the stream before our method has a chance to start or finish what it wants to do.

Solution:

    internal async Task<DataFormat> TestAsync()
    {
        using (var stream = File.Open("test.dat", FileMode.Open, FileAccess.Read, FileShare.Read))
        {
            return await StreamProcessingUtil.DoSomethingAsync(stream);
        }
    }