Running test_idle is supposed to cause the tests in Lib/idlelib/idle_test to be run.  Unfortunately, under 2.7, when test.regrtest is used as the test runner, either directly or via "make test" (which buildbots use), the idlelib tests are currently silently skipped.  This can be seen by running with -v and observing that nothing is run:

python -m test.regrtest -v -uall test_idle

The problem is that test_idle.py is depending on regrtest support of the load_tests protocol; that support was only added to regrtest in 3.3.  Without changes to regrtest for 2.7, test_idle needs to define test_main as other tests do.  The attached patch seems to fix the problem.