One of the popular favorites at thoughtbot, at least in the boost team, is
It helps you find when/where (in which commit) a certain part of the code broke.
It’s pretty magic and this is how you use it.
git bisect start
Git checkout the branch that you know is good, where the code is working and:
git bisect good
Git checkout the broken branch and set it as bad:
git bisect bad
This can be accomplished in various ways, say you know something is currently broken
main, you can declare it from a different branch:
git bisect bad main
Or you want to go back in time, so you can checkout the SHA of a commit that you know is bad, and maybe go 3 step back and use:
git bisect good HEAD~3
Then git starts doing its magic.
Keep going, running
git bisect good or
bad in case you’re “going back or
At the end you’ll see what was the commit that broke the code. Yay.
git bisect reset
In the docs there are a lot of additional nifty things you can do, but this is already cool basic usage that gets the job done.