TESTS: Improve test execution speed, upgrade NUnit (or switch to XUnit), incorporate FsUnit

[alsi-lawr]

Proposal:

In NUnit, you can already tell the test runner to run tests in parallel using a single directive in the root test assembly. This is an easy win for improving test execution.

There are multiple tests that can reuse the same client to avoid the ~5s startup penalty of newing up a client every time. We can move this into a per-fixture OneTimeStartup assignment and share the C# test project code amongst the tests. This is reasonable where we're not actually affecting the file system with the client, as is the case in a lot of these tests. We can then set each fixture to run sequentially to avoid parallel calls to the same client that might cause race conditions.

NUnit is currently on an older major version (3.14). If we bump it to v4+, we can utilise FsUnit for beautiful assertion syntax like this:

myString |> should equal "hello world"

Instead of:

Assert.AreEqual("hello world", myString)

I'm more than happy to take this on

[razzmatazz]

I wonder if there is a more functional approach to the fixture problem than doing a class.

Also, I am not really sure if myString |> should equal "hello world is more beautiful than Assert.AreEqual(), but I guess it would grow on me..

[alsi-lawr]

I wonder if there is a more functional approach to the fixture problem than doing a class.

Also, I am not really sure if myString |> should equal "hello world is more beautiful than Assert.AreEqual(), but I guess it would grow on me..

To me, it's just more like regular English. It's the same principle behind FluentAssertions or Shouldly.

Putting the tests into fixtures also allows you to have parallelisation scoped to the fixture by default, which makes it simpler to set up