'The L{LocalRefResolver.resolving} context manager raises an exception
when entered.'

def test_resolvingRaisesError(self):

    resolver = LocalRefResolver(base_uri='', referrer={})
    context = resolver.resolving('http://json-schema.org/schema')
    e = self.assertRaises(RefResolutionError, context.__enter__)
    self.assertIsInstance(e.args[0], SchemaNotProvided)
