Actual Behavior

MockHandler doesn't offer a way of resetting the internal queue. There are testing scenarios where the handler has been initialized in the setUp() method of a test suite, to avoid duplication, and some specific responses are queued up as the default behavior but then you have tests which need to queue up something different (i.e a request error).

In this cases, it is not possible to reuse the handler defined in setUp(), and instad, it is required to re-instantiate and re-wire a handler and the dependencies all over again.

Expected Behavior

To avoid having to wire and set up the handler all over again, it would be great to expose a way to reset the internal queue in the MockHandler instance, and then just queue the new response(s).

This PR adds a method to MockHandler to reset the internal queue. Calling$handler->reset(); would reset the internal array and allow the tester to queue up new responses.