Predicate based matching on HttpRequestMessage

[Joshhua5]

Something like this would solve all of our needs for matching, if you approve of the direction, I'll go ahead and add the documentation and additional tests.

[sandermvanvliet]

I'm not sure I would want to take this direction with the package because it moves away from the expressiveness I had in mind when I built this.
I appreciate that this is an approach that would allow for any kind of matching but at it comes at the cost of readability.

Let me try to explain what I mean by that.

Consider someone stumbling on this library (or in existing code via IntelliSense) and seeing the AndWhen() method, they might be inclined to write something like this:

handler
    .RespondTo()
    .Get()
    .AndWhen(req => req.Path == "whatever" &&
        reg.Headers.Accept == "text/plain" &&
        req.Headers["Cookie"] == "testcookie=1");

which is (again, in my opinion) harder to understand than it's equivalent:

handler
    .RespondTo()
    .Get()
    .ForUrl("whatever")
    .Accepting("text/plain")
    .AndCookie("testcookie", "1");

While this may seem contrived I want to push people into the pit of success and guide to the intended usage.