Although some testing tools and frameworks exist (like Tabular Editor 2/3 or PQL), my day-to-day use cases felt like using a shotgun to catch fish (sure, you can do it, but a rod would have been better). So, I talked to some people and built a Power BI error checker where you can freeze a .pbip at any point in time (consider it the golden source of truth), and if you or someone else (person or AI) changes something that you don't like, you see exactly what changed in your data.
You can also add your own tests using simple YAML instructions (similar to DAX) or drag-and-drop tools.
If you work with Power BI and you are sick of digging through tables to understand what went wrong, this tool might be for you!
It is open-source, written in Python, and it is pretty fast at catching issues. If you have any feedback/comments, I'd be glad to hear them.