'``transform`` raises ``TypeError`` if the object at the supplied
``path`` does not provide ``_IEvolvable``.'

def test_transform_typeerror(self):

    proxy = _TransformProxy(pmap({'a': 1}))
    e = self.assertRaises(TypeError, proxy.transform, ['a'], 2)
    self.assertEqual('1    does    not    provide    _IEvolvable', e.message)
