'A convenience method for the user as a way to shorten up the
often repetitious calls to create the same authentication.
Raises ``NotImplementedError`` by default.
Usage::
class MyResourceTestCase(ResourceTestCase):
def get_credentials(self):
return self.create_basic(\'daniel\', \'pass\')
# Then the usual tests...'

def get_credentials(self):

    raise NotImplementedError(u'You    must    return    the    class    for    your    Resource    to    test.')
