Testing changes made to settings and mappings

I'm using the C# NEST client and I would like to know which tools and methods I can use to test my search queries each time I make changes to my settings and mappings. At the moment I'm having a nightmare with the changes I'm making as they are quite complicated and I have to keep manually testing to make sure I've not broken anything.

Any advice and information such as web links would be much appreciated, ideally for the C# .NET platform.