Use .ContinueWith instead of finally for removal.

[tillig]

This allows non-async/await and Task-based handling to complete and still remove the scope without the try/finally removing it before the task is finished.

Based on comments for #17.

[tillig]

@russellfoster @srogovtsev Give this a look, I think I got it. If you don't have time, no biggie, but thought you'd be interested. Plus, I have to admit my Task semantics are a little rusty since async/await came along. I had to come up with some pretty contrived examples to run tests on it.

[alistairjevans]

Approved with two questions. 👍

[srogovtsev]

You'd also need a test for cancelled tasks, something like:

var cancellationTokenSource = new CancellationTokenSource();
cancellationTokenSource.Cancel();

var fakeHandler = new FakeInnerHandler(_ =>
        {
            return Task.Factory.StartNew<HttpResponseMessage>(async () =>
            {
                //this should cancel immediately
                await Task.Delay(-1, cancellationTokenSource.Token);
                //we never get here, but the compiler doesn't know it
               return new HttpResponseMessage(HttpStatusCode.OK);
            });
        });

[tillig]

• Added continuation options to specify the scheduler and that the continuation should run synchronously.
• Added async/await test equivalents of the Task tests. This made the original test for scope removal redundant because the same scenario is being tested with the new tests.

[tillig]

Pushing this through. I think I got everything and it should at least unblock folks who were affected by the issue. We can tweak which scheduler to use later if we need to.