A modern programming language that makes developers happier.

kotlinlang

We have projects using plain junit5 and projects using kotlintest. The first is very flexible alone with testfactories, extensions and testng-like setup/test instance lifecycle. I am very satisfied how our partly very complex tests look like, combined with just kotlin code to hide some boilerplate. It's also very nice for people that aren't too comfortable with extensive kotlin dsls. the latter allows for some nice to read tests with the right balance between nice and crazy that are not tied to junit structures. To be honest, we already ran into some problems with kotlintest/dsls for example when you want to abstract a little bit and use own extension functions, so i would recommend junit5 and assertj or sth similar. Grain of salt and so in, we have some java oriented people and so on.