bpo-45229: Remove test_main in many tests (GH-28405)

Instead of explicitly enumerate test classes for run_unittest()
use the unittest ability to discover tests. This also makes these
tests discoverable and runnable with unittest.

load_tests() can be used for dynamic generating tests and adding
doctests. setUpModule(), tearDownModule() and addModuleCleanup()
can be used for running code before and after all module tests.

1 files changed, 2 insertions, 8 deletions

diff --git a/Lib/test/test_mailbox.py b/Lib/test/test_mailbox.py
index 8a5d692462..604fc4525f 100644
--- a/Lib/test/test_mailbox.py
+++ b/Lib/test/test_mailbox.py
@@ -2300,15 +2300,9 @@ class MiscTestCase(unittest.TestCase):
                              not_exported={"linesep", "fcntl"})
 
 
-def test_main():
-    tests = (TestMailboxSuperclass, TestMaildir, TestMbox, TestMMDF, TestMH,
-             TestBabyl, TestMessage, TestMaildirMessage, TestMboxMessage,
-             TestMHMessage, TestBabylMessage, TestMMDFMessage,
-             TestMessageConversion, TestProxyFile, TestPartialFile,
-             MaildirTestCase, TestFakeMailBox, MiscTestCase)
-    support.run_unittest(*tests)
+def tearDownModule():
     support.reap_children()
 
 
 if __name__ == '__main__':
-    test_main()
+    unittest.main()