Migrate existing NUnit tests to xUnit

[vzarytovskii]

Migrate existing NUnit test suites (mostly UnitTest ones), to xUnit.

[sergey-tihon]

@vzarytovskii can you please comment why? What is wrong with NUnit?

[vzarytovskii]

@sergey-tihon

Nothing wrong with NUnit, since we've started migrating old fsharpqa and Cambridge suites to the new standard dotnet test suites, we've just chosen xUnit as default framework.

I guess, the main reason is it's already widely adopted in most of the exiting .NET projects (for example Roslyn, runtime, sdk, aspnetcore), so we want have same experience across all projects.

Also, I, personally find it a bit less verbose, than NUnit, and a bit easier to extend (but again, it is probably just my subjective take on it).

[vzarytovskii]

@sergey-tihon Please, let me know if you would like to chat about it, i would gladly discuss it :)

[sergey-tihon]

I am not strongly agains xUnit, just wonder why some .net project choose xUnit over NUnit and what benefits come with xUnit.

I personally less experienced with xUnit, but when I tried to port some of my projects to xUnit I stuck with inability execute Theory in parallel what is easy doable in NUnit

If you have samples where xUnit is less verbose and easier to extent on top of you mind, I will be glad to take a look.