[3.6] bpo-31243: Fixed PyArg_ParseTuple failure checks. (GH-3171) (#3233)

(cherry picked from commit ba7d7365215d791025d1efd25393c91404f2cfc8)

1 files changed, 20 insertions, 0 deletions

diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 7057c92..08c041e 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -3191,6 +3191,26 @@ class TextIOWrapperTest(unittest.TestCase):
         t = _make_illegal_wrapper()
         self.assertRaises(TypeError, t.read)
 
+        # Issue 31243: calling read() while the return value of decoder's
+        # getstate() is invalid should neither crash the interpreter nor
+        # raise a SystemError.
+        def _make_very_illegal_wrapper(getstate_ret_val):
+            class BadDecoder:
+                def getstate(self):
+                    return getstate_ret_val
+            def _get_bad_decoder(dummy):
+                return BadDecoder()
+            quopri = codecs.lookup("quopri")
+            with support.swap_attr(quopri, 'incrementaldecoder',
+                                   _get_bad_decoder):
+                return _make_illegal_wrapper()
+        t = _make_very_illegal_wrapper(42)
+        self.assertRaises(TypeError, t.read, 42)
+        t = _make_very_illegal_wrapper(())
+        self.assertRaises(TypeError, t.read, 42)
+        t = _make_very_illegal_wrapper((1, 2))
+        self.assertRaises(TypeError, t.read, 42)
+
     def _check_create_at_shutdown(self, **kwargs):
         # Issue #20037: creating a TextIOWrapper at shutdown
         # shouldn't crash the interpreter.