I totally agree with this, and writing a test suite also happens to be a great exercise in learning a new legacy code base. I’d also suggest following this up

I totally agree with this, and writing a test suite also happens to be a great exercise in learning a new legacy code base. I’d also suggest following this up with a solid monitoring system so you can be confident any exceptions / performance regressions are caught. Confidence in new deployed code and reduce time to find any faults is one of the most important aspects of development productivity.