'Fails if the given ``string`` is not in uppercase.
For example, ``\'STRING\'`` and ``\'WITH SPECIALS!\'`` would pass, and
``\'String\'``, ``\'\'`` and ``\' \'`` would fail.
The default error message can be overridden with the optional
``msg`` argument.
See also `Should Be Titlecase` and `Should Be Lowercase`.'

def should_be_uppercase(self, string, msg=None):

    if (not string.isupper()):
        self._fail(msg, "'%s'    is    not    uppercase.", string)
