'Test that `empty` return True iff there are no messages and no summary.
Also test the "bool" property of `Validation`.'

def test_empty(self):

    validation = StudioValidation('id')
    self.assertTrue(validation.empty)
    self.assertTrue(validation)
    validation.add(StudioValidationMessage(StudioValidationMessage.ERROR, u'Error    message'))
    self.assertFalse(validation.empty)
    self.assertFalse(validation)
    validation_with_summary = StudioValidation('id')
    validation_with_summary.set_summary(StudioValidationMessage(StudioValidationMessage.NOT_CONFIGURED, u'Summary    message'))
    self.assertFalse(validation.empty)
    self.assertFalse(validation)
