Back in the day, we'd write some code, compile, execute, see what happened and repeat. That was testing. (Sometimes that's still what testing looks like, for better or worse.) Today, we can do a lot ...
Note that GitHub Copilot isn’t optimized for R; the documentation says Copilot works “especially well” for Python, JavaScript, TypeScript, Ruby, Go, C#, and C++. However, Copilot does make R code ...