raise an ValueError in getvalue() on closed StringIO (closes #12161)

Thanks for Catalin Iacob for the patch.

Lib/StringIO.py

@@ -266,6 +266,7 @@ class StringIO:
         8th bit) will cause a UnicodeError to be raised when getvalue()
         is called.
         """
+        _complain_ifclosed(self.closed)
         if self.buflist:
             self.buf += ''.join(self.buflist)
             self.buflist = []

Lib/test/test_StringIO.py

@@ -100,6 +100,10 @@ class TestGenericStringIO(unittest.TestCase):
         self._fp.close()
         self.assertRaises(ValueError, self._fp.next)
 
+    def test_getvalue(self):
+        self._fp.close()
+        self.assertRaises(ValueError, self._fp.getvalue)
+
 class TestStringIO(TestGenericStringIO):
     MODULE = StringIO
 

Misc/ACKS

@@ -382,6 +382,7 @@ Eric Huss
 Jeremy Hylton
 Gerhard Häring
 Fredrik Håård
+Catalin Iacob
 Mihai Ibanescu
 Lars Immisch
 Bobby Impollonia

Misc/NEWS

@@ -83,6 +83,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #12161: Cause StringIO.getvalue() to raise a ValueError when used on a
+  closed StringIO instance.
+
 - Issue #12182: Fix pydoc.HTMLDoc.multicolumn() if Python uses the new (true)
   division (python -Qnew). Patch written by Ralf W. Grosse-Kunstleve.