Migrate test project to XUnit?

[kostrse]

Very minor thing, just for convenience, to make the project more portable?
Tried to quickly build in Mono, and found that unit-test project depends on MSTest.

[kostrse]

build.cmd / build.sh in the root of the repo to build and run unit-tests from command line would be useful too 😄 (FAKE / Cake)

[Pxtl]

I'm not familiar w XUnit, I've only used MSTest personally. Does XUnit require an extension for VS integration?

Pull requests are welcome as long as the XUnit workflow is painless.