less languages/frameworks to learn => easier start for contributors
less languages/frameworks to support/maintain => less headache to me (CodeNarc and its plugin have issues: #508, #539, #994), less time I need to spend on this (for example, updating Gmaven plugin (#958), Groovy (#938), Spock (#761), CodeNarc (#1187), integration to our CI (#1479))
I noticed that tests on Spock/Groovy are running slower in IDEA than JUnit ones
The community seems inactive so the future is unclear and features/updates get released longer
JUnit has rich ecosystem
I found that syntax sugar doesn't outweight all aforementioned
Rationale:
TODO:
junit-jupiter-engine
and exclude (and ban?)junit
from other dependencies