#17479: merge with 3.3.

Lib/test/test_io.py

@@ -3234,7 +3234,7 @@ class PySignalsTest(SignalsTest):
     test_reentrant_write_text = None
 
 
-def test_main():
+def load_tests(*args):
     tests = (CIOTest, PyIOTest,
              CBufferedReaderTest, PyBufferedReaderTest,
              CBufferedWriterTest, PyBufferedWriterTest,
@@ -3267,7 +3267,8 @@ def test_main():
             for name, obj in py_io_ns.items():
                 setattr(test, name, obj)
 
-    support.run_unittest(*tests)
+    suite = unittest.TestSuite([unittest.makeSuite(test) for test in tests])
+    return suite
 
 if __name__ == "__main__":
-    test_main()
+    unittest.main()

Misc/NEWS

@@ -1035,6 +1035,9 @@ Tests
 
 - Issue #16836: Enable IPv6 support even if IPv6 is disabled on the build host.
 
+- Issue #17479: test_io now works with unittest test discovery.
+  Patch by Zachary Ware.
+
 - Issue #17066: test_robotparser now works with unittest test discovery.
   Patch by Zachary Ware.