fsharp-hedgehog-xunit VS fsharp-hedgehog

I totally agree - the ability to write tests with random data is fantastic. Here's an example with Hedgehog.Xunit (shameless plug) that's somewhat similar to your gzip example in that it tests the inverse property of List.rev:

Disclaimer: I maintain Hedgehog.XUnit.

I just "finished" building Hedgehog.Xunit, which adds some convenience attributes to Hedgehog, a property-based testing library similar to FsCheck. The distinguishing feature is that shrinking comes for free with Hedgehog, whereas you have to customize shrinkers in FsCheck. An blog comparing the two. There's also a cleaner API; no more Arb.

Unit testing: I personally use FsUnit, specifically FsUnit.Xunit. There's some other libraries like Expecto and Hedgehog (property testing), but I haven't found a reason to use them. I recently started experimenting a little with Hedgehog. FsUnit integrates well into Visual Studio, since it sits nicely on top of NUnit and xUnit, and it's done everything I've needed so far.

Looks cool. Is there a reason why you didn't use FsCheck or Hedgehog? They're built to generate random data for testing, and can return the seed if a test fails so you can rerun the test with the exact same data once you figure out what the problem is - which is useful if the failure condition is rare.

Haskell has QuickCheck and Hedgehog, and dotnet has both as well. F# is favored, but there's C# interop.

Dotnet has FsCheck and Hedgehog. Both are primarily aimed at F#, but C# is supported as well.

Hedgehog