Right now, the tests for the unittest package are under the package directory instead of Lib/test where we have most of the other tests.
There are some other packages that do the same thing, each for their own reason.
The corresponding bug report is #10572 (opened by Michael Foord).
R. David Murray was +1 for moving email tests, Barry deferred to him, Brett was +0 for importlib, and I was ±0 for distutils. Maintainers of ctypes, json, lib2to3 and sqlite3 haven’t yet expressed themselves.