I have used test -m, but a point in favor of this proposal, for other people, is consistency with running unittest

f:\dev\3x>python -m unittest idlelib.idle_test.test_autocomplete.AutoCompleteTest.test_init
Running Debug|Win32 interpreter...
.
----------------------------------------------------------------------
Ran 1 test in 0.176s

However, the current patch appears to be useless for test modules, like test_idle, that use load_tests to discover tests, as none of the test modules or classes discovered are attributes of the main test module.  The following both fail.

python -m test test_idle.test_autocomplete
python -m test test_idle.AutoCompleteTest