The first (actually second, of course there was an immediate patch needed) release of GUT for Godot 4 is now available in the Asset Library and Github. To see how GUT has changed for Godot 4 read this: https://bitwes.github.io/GutWiki/Godot4/New-For-Godot-4.html.
GUT is a Unit testing framework for Godot. This release brings all your favorite asserts, doubling, stubbing, and spying goodness to Godot 4. It may still be a little rough around the edges, and the wiki isn't fully updated yet...but it's been released and is ready for consumption!
Asset Library: https://godotengine.org/asset-library/asset/1709
Github (godot_4 branch): https://github.com/bitwes/Gut/tree/godot_4
GUT 9 Wiki: https://bitwes.github.io/GutWiki/Godot4/Home.html
Feedback is always welcome. May all your reds turn green and your refactors remain green.