So now I'm really not sure what happened, but running previous tests now comes back with the same TokenMismatchException and additionally, running any test wipes out my MySQL databases. It's using DatabaseMigrations, but previously this was only taking effect on sqlite when testing, so I don't know what's happening that all of my testing stuff is falling apart.
My phpunit.xml hasn't changed--it is still set to use an in-memory sqlite database when testing.