public void TestWithCancellation() { var cts = new CancellationTokenSource(); cts.CancelAfter(TimeSpan.FromMilliseconds(25)); Assert.ThrowsAny <OperationCanceledException>( () => { try { var provider = new MakoProvider(); var items = provider .GetNews(cts.Token) .Result .ToList(); } catch (AggregateException e) { List <OperationCanceledException> canceledExceptions = e.InnerExceptions .Cast <OperationCanceledException>() .ToList(); if (canceledExceptions.Any()) { throw canceledExceptions.First(); } } }); }