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, 6 insertions, 9 deletions

diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index cdca5a8..4269b0e 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -9,7 +9,7 @@ from array import array
 from weakref import proxy
 from functools import wraps
 
-from test.support import run_unittest, cpython_only, swap_attr, gc_collect
+from test.support import cpython_only, swap_attr, gc_collect
 from test.support.os_helper import (TESTFN, TESTFN_UNICODE, make_bad_fd)
 from test.support.warnings_helper import check_warnings
 from collections import UserList
@@ -606,15 +606,12 @@ class PyOtherFileTests(OtherFileTests, unittest.TestCase):
             self.assertNotEqual(w.warnings, [])
 
 
-def test_main():
+def tearDownModule():
     # Historically, these tests have been sloppy about removing TESTFN.
     # So get rid of it no matter what.
-    try:
-        run_unittest(CAutoFileTests, PyAutoFileTests,
-                     COtherFileTests, PyOtherFileTests)
-    finally:
-        if os.path.exists(TESTFN):
-            os.unlink(TESTFN)
+    if os.path.exists(TESTFN):
+        os.unlink(TESTFN)
+
 
 if __name__ == '__main__':
-    test_main()
+    unittest.main()