I've been dabbling on and off with Visual Studio's Live Unit Testing feature. Introduced in 2017, it's arguably a sherlocking of NCrunch, with all that entails: a first party implements something that used to be a third party's business model, and also gets to integrate it better (since, y'know, they're the first party). I hope the NCrunch folks are doing well.
IHateRegex has another regular expressions playground. I was more familiar with RegExr and regex101, and, back in the day when Silverlight still ran on macOS, I enjoyed running Regex Hero's online tester. Because it was written in Silverlight, it matched .NET's regex engine precisely, because, well, that's what it was running on.