Enable a virtual method to clean up data after a smoke test

[geoffroybraun]

For now on, when a smoke test needs to clean up some data, it must be part of the scenario or triggered using the "IDisposable" interface, which might not be the suitable solution. Having a virtual method such as "CleanUp" would allow a smoke test to run a scenario and perform an action right after it to avoid having tests data in production environments.