[HenrikB]

Maybe also:

- Write lots of tests with high test coverage before migration. Then you can rely on them on a continuous basis to make sure any updates do not break the existing functionality

[all2]

This sounds like it could be a fun exercise all by itself (I'm a test engineer, and I enjoy testing :D )

[pflanze]

Yes, extending the test suite may definitely be worthwhile. Also, using AFL+ to collect non-crashing test cases can make this quick and somewhat exhaustive (while admittedly not giving as easy hints about what might be broken than manually created tests would).

Just in case you're interested in joining the sessions that I initiated, see https://news.ycombinator.com/item?id=30973570

[stazz1]

This is the only way to ensure sanity is maintained through this arduous process.