Gui.cs: Implement unit and regression tests

[tig]

This project desperately needs a set of automated unit and regression tests.

[tig]

My ideas:

• Use xunit - I've used it before and dig it.
• Ensure all tests run as part of CI/CD - I would prefer we use Github actions over Azure Pipelines or TravisCI just to keep things simple and contained.
• I envision a set of tests that leverage UICatalog Scenarios - build a mock ConsoleDriver that lets tests specify how a console buffer should look and then check after the Scenario has run.

[tig]

I now have a plan for the first set of automated tests.

• Define a set of View unit tests
  
  
  
  • Initialize Absolute
  
  
  • Initialize Computed
  
  
  • For each typical DimPos scenario set X, Y, Height, Width and verify no crashes
  
  
  • For anything with a Text or Title property, throw different strings at 'em ensuring no crashes (see #617)
  
  
  • Etc...
  
  
• I will leverage the code in the new AllViewsTester to dynamically run through every View derived class and automate most of the above so one test set runs against all controls.
• I'll enable per-control tests

This will be the start. I'm willing to bet that once the infrastructure is in place, having more people contribute tests will be contagious.

[BDisp]

This will be the start. I'm willing to bet that once the infrastructure is in place, having more people contribute tests will be contagious.

I look forward to using it. I am a great advocate of regression testing and this initiative makes it much more contagious, believe me. Thank you.

[migueldeicaza]

Charlie asked me to comment on this.

I agree that we need unit tests, but have struggled to come up with a plan.

XUnit sounds like a fine choice

[tig]

[tig]

Woot! Closed with #648