If it's got a web interface I suggest starting with browser-based testing like Selenium. It won't be as good as unit tests but will catch the obvious fuckups. I

If it's got a web interface I suggest starting with browser-based testing like Selenium. It won't be as good as unit tests but will catch the obvious fuckups. I plan on doing this to a legacy project at my employer's and I already know it would've caught a few production fuckups we had lately - 500 error on the homepage, etc. This also means you don't even need to be familiar with the code base, but just know how to use the web interface as a normal user would.