SF patch #1359365: file and cStringIO raise a ValueError when next() is called

after calling close(). Change StringIO, so that it behaves the same way.

Lib/StringIO.py

@@ -72,8 +72,7 @@ class StringIO:
         method is called repeatedly. This method returns the next input line,
         or raises StopIteration when EOF is hit.
         """
-        if self.closed:
-            raise StopIteration
+        _complain_ifclosed(self.closed)
         r = self.readline()
         if not r:
             raise StopIteration

Lib/test/test_StringIO.py

@@ -87,6 +87,8 @@ class TestGenericStringIO(unittest.TestCase):
             eq(line, self._line + '\n')
             i += 1
         eq(i, 5)
+        self._fp.close()
+        self.assertRaises(ValueError, self._fp.next)
 
 class TestStringIO(TestGenericStringIO):
     MODULE = StringIO