def test_sustituir_tipo_base(self):
s = Sustitucion()
s.push(Var("a"), Fun(Var("b"), Int()))
self.assertEqual(str(s.sustituir(Int())), str(Int()))
self.assertEqual(str(s.sustituir(Bool())), str(Bool()))
def test_sustituir_paren(self):
s = Sustitucion()
s.push(Var("a"), Fun(Var("b"), Int()))
self.assertEqual(str(s.sustituir(Paren(Var("a")))), str(Paren(Fun(Var("b"), Int()))))
def test_sustituir_vacio(self):
s = Sustitucion()
self.assertEqual(str(s.sustituir(Fun(Var("a"), Var("b")))), str(Fun(Var("a"), Var("b"))))
