Registered just so I could vote on this. I am amazed it has so little votes and activity. As with the previous commenter, I would like to do unit test for classes that use Session.

Wow, I'm trying to add a unit test on my connection class that use WinSCP and I would like an interface.

It's very important, I use WinSCP dll often to do many things

I voted for this enhancement

Thanks

You can vote for the feature in the tracker:
Issue 856 – Define and implement interface for the .NET library

Most of the action with the .NET assembly is via the Session class.
It would be nice to have Session implement an interface (e.g. ISession?) representing the public methods to allow developers to easily mock out the library for unit testing.