def test_assign_variable_int(self):
a = Ambiente()
a.extend(Variable('x'), Var('a'))
s = Sustitucion()
s.push(Var('a'), Int())
self.assertEqual(a.assign(Variable('x'), Int()), s)
def test_extend_find_non_existing(self):
a = Ambiente()
a.extend(Variable('x'), Int())
self.assertEqual(a.find(Variable('y')), None)
