public async Task TestParallelThrottling()
{
List <int> list = Enumerable.Range(0, 100).ToList <int>();
IReadOnlyList <int> col = new ReadOnlyCollection <int>(list);
var count = 0;
var concurrentCount = new ConcurrentStack <int>();
col.ParallelForEachAsync <int>(10, async x =>
{
concurrentCount.Push((Interlocked.Increment(ref count)));
await Task.Delay(1000);
concurrentCount.Push((Interlocked.Decrement(ref count)));
});
Assert.AreEqual(concurrentCount.Max(), 10);
}