In impress-2020, we do a big slow query to figure out which users have
been active in trades recently. Now, we cache that timestamp on the
User model.
This won't have any immediate effect; it's to clear the way for Classic
DTI to receive the better trade ratios feature people like from 2020.
I also added some unit testing infra because I finally wanted it! for
all the ways you can trigger this timestamp lol
Note too that this is a bit of an unusually complex migration, but my
hope is that the batching and query structure and such helps it run
surprisingly fast! 🤞
Look, I'll be real, I have literally not run these automated tests in
probably like a whole decade. Most of these files are empty, the ones
that aren't seem basically trivial, and I bet half of it would fail
anyway.
If I wanted to do real automated testing, I would basically want to
start from scratch anyway, and apply coverage I can trust to the areas
I actually care about.
Until then, I feel like these gems and files are mostly just clutter,
and I don't like them being One More Barrier To Entry. Goodbye, unused
complexity!
