'Verify that everything written to the fake file C{self.out} was a
C{str}.  Also, restore the default string encoding to its previous
setting, if it was modified by L{setUp}.'

def tearDown(self):

    for chunk in self.out:
        self.assertIsInstance(chunk, str, ('%r    was    not    a    string' % (chunk,)))
    if (self._origEncoding is not None):
        sys.setdefaultencoding(self._origEncoding)
        del sys.setdefaultencoding
