Previously, we had the tests split so that those which needed access to driver internals were defined directly within the package and all others were defined in the unit test directory. However, now that we're using a read/write lock to ensure that tests that define failpoints run exclusively instead of concurrently with other tests using the database, we need to share the lock between all tests that make connections to the database. Because some of them still need access to driver internals, the simplest solution is to move all of the tests outside the package into the driver itself. (Note that they will still be compiled with the #[cfg(test)] attribute like the tests already within the driver, so they won't be pulled in when a user depends on the package)