Fsharp Testing

This covers the full F# testing stack: xUnit for structure, FsUnit for F# friendly assertions, Unquote for quotation based failure messages that actually tell you what broke, and FsCheck for property based testing. You get working examples of async tests with task, parameterized theories, custom generators, and both function stub patterns (the F# way) and NSubstitute for .NET interfaces. The integration testing section shows WebApplicationFactory setup with in-memory databases. Use this when you're setting up a new F# project's test suite or when your existing tests feel clunky because you're fighting against C# patterns. The anti-patterns section alone is worth reading if you've been writing Thread.Sleep in your async tests.