'A ClearableFileInput should not mask exceptions produced while
checking that it has a value.'

def test_html_does_not_mask_exceptions(self):

    class FailingURLFieldFile:
        @property
        def url(self):
            raise ValueError('Canary')
        def __str__(self):
            return 'value'
    with self.assertRaisesMessage(ValueError, 'Canary'):
        self.widget.render('myfile', FailingURLFieldFile())
