Issue #18258: Fix test discovery for test_codecmaps_*.
diff --git a/Lib/test/multibytecodec_support.py b/Lib/test/multibytecodec_support.py
index 51ca3bd..51f5b54 100644
--- a/Lib/test/multibytecodec_support.py
+++ b/Lib/test/multibytecodec_support.py
@@ -277,8 +277,7 @@
     supmaps = []
     codectests = []
 
-    def __init__(self, *args, **kw):
-        unittest.TestCase.__init__(self, *args, **kw)
+    def setUp(self):
         try:
             self.open_mapping_file().close() # test it to report the error early
         except (OSError, HTTPException):
diff --git a/Lib/test/test_codecmaps_cn.py b/Lib/test/test_codecmaps_cn.py
index 76632a2..8b84c14 100644
--- a/Lib/test/test_codecmaps_cn.py
+++ b/Lib/test/test_codecmaps_cn.py
@@ -25,8 +25,5 @@
                  'trunk/charset/data/xml/gb-18030-2000.xml'
 
 
-def test_main():
-    support.run_unittest(__name__)
-
 if __name__ == "__main__":
-    test_main()
+    unittest.main()
diff --git a/Lib/test/test_codecmaps_hk.py b/Lib/test/test_codecmaps_hk.py
index 9570af2..12aada1 100644
--- a/Lib/test/test_codecmaps_hk.py
+++ b/Lib/test/test_codecmaps_hk.py
@@ -12,8 +12,5 @@
     encoding = 'big5hkscs'
     mapfileurl = 'http://people.freebsd.org/~perky/i18n/BIG5HKSCS-2004.TXT'
 
-def test_main():
-    support.run_unittest(__name__)
-
 if __name__ == "__main__":
-    test_main()
+    unittest.main()
diff --git a/Lib/test/test_codecmaps_jp.py b/Lib/test/test_codecmaps_jp.py
index fa93f12..1c66d80 100644
--- a/Lib/test/test_codecmaps_jp.py
+++ b/Lib/test/test_codecmaps_jp.py
@@ -59,8 +59,5 @@
     mapfileurl = 'http://people.freebsd.org/~perky/i18n/SHIFT_JISX0213.TXT'
 
 
-def test_main():
-    support.run_unittest(__name__)
-
 if __name__ == "__main__":
-    test_main()
+    unittest.main()
diff --git a/Lib/test/test_codecmaps_kr.py b/Lib/test/test_codecmaps_kr.py
index e0bf716..404d74e 100644
--- a/Lib/test/test_codecmaps_kr.py
+++ b/Lib/test/test_codecmaps_kr.py
@@ -36,8 +36,5 @@
     pass_enctest = [(b'\\', '\u20a9')]
     pass_dectest = [(b'\\', '\u20a9')]
 
-def test_main():
-    support.run_unittest(__name__)
-
 if __name__ == "__main__":
-    test_main()
+    unittest.main()
diff --git a/Lib/test/test_codecmaps_tw.py b/Lib/test/test_codecmaps_tw.py
index 4d27080..9bf8340 100644
--- a/Lib/test/test_codecmaps_tw.py
+++ b/Lib/test/test_codecmaps_tw.py
@@ -26,8 +26,5 @@
         (b"\xFFxy", "replace",  "\ufffdxy"),
     )
 
-def test_main():
-    support.run_unittest(__name__)
-
 if __name__ == "__main__":
-    test_main()
+    unittest.main()