'Test fallback to None'

def testFallbackWithoutWidgets(self):

    rf = S3ReusableField('test', 'integer')
    field = rf()
    self.assertEqual(field.widget, None)
    field = rf(widget='default')
    self.assertEqual(field.widget, None)
    self.assertRaises(NameError, rf, widget='alternative')
    field = rf(widget=self.widget1)
    self.assertEqual(field.widget, self.widget1)
    self.assertRaises(NameError, rf, widget='other')
