def test_proper_cons(self):
a = cons(2, nil)
b = cons(1, a)
c = cons(0, b)
self.assertTrue(a.is_proper())
self.assertTrue(b.is_proper())
self.assertTrue(c.is_proper())
self.assertFalse(a.is_recursive())
self.assertFalse(b.is_recursive())
self.assertFalse(c.is_recursive())
self.assertEqual(car(b), 1)
self.assertEqual(car(cdr(b)), 2)
self.assertEqual(car(c), 0)
self.assertEqual(car(cdr(c)), 1)
self.assertEqual(car(cdr(cdr(c))), 2)
x, (y, (z, n)) = c
self.assertEqual(x, 0)
self.assertEqual(y, 1)
self.assertEqual(z, 2)
self.assertEqual(n, nil)
x, y, z = c.unpack()
self.assertEqual(x, 0)
self.assertEqual(y, 1)
self.assertEqual(z, 2)
self.assertEqual(c.count(), 3)
self.assertSequenceEqual(list(c.unpack()), [0, 1, 2])
self.assertSequenceEqual(tuple(c.unpack()), (0, 1, 2))
self.assertEqual(str(c), "(0 1 2)")
self.assertEqual(repr(c), "cons(0, cons(1, cons(2, niltype())))")
self.assertEqual(car(a), 2)
self.assertEqual(cdr(a), nil)
self.assertEqual(car(b), 1)
self.assertEqual(cdr(b), a)
w = cons(0, cons(1, cons(2, nil)))
self.assertEqual(c, w)
self.assertEqual(w, c)
u = cons(99, c)
v = cons(99, w)
self.assertEqual(u, v)
self.assertEqual(v, u)
self.assertNotEqual(cons(99, nil), u)
self.assertNotEqual(u, cons(99, nil))
def test_recursive_cons(self):
a = cons(1, cons(2, cons(3, nil)))
setcdr(cdr(cdr(a)), a)
self.assertTrue(a.is_proper())
self.assertTrue(a.is_recursive())
self.assertEqual(car(a), car(cdr(cdr(cdr(a)))))
self.assertEqual(str(a), "(1 2 3 ...)")
self.assertEqual(repr(a), "cons(1, cons(2, cons(3, ...)))")
b = cons(0, a)
c = cons(0, a)
self.assertEqual(b, c)
self.assertNotEqual(a, b)
self.assertNotEqual(a, c)
z = cons(1, cons(2, cons(3, nil)))
setcdr(cdr(cdr(z)), z)
self.assertEqual(a, z)
self.assertEqual(z, a)
def test_nil(self):
# singleton nil check
self.assertEqual(id(nil), id(niltype()))
self.assertEqual(id(niltype()), id(niltype()))
self.assertTrue(nil is niltype())
# behavior
self.assertIsInstance(nil, cons)
self.assertFalse(nil)
self.assertEqual(str(nil), "()")
self.assertEqual(repr(nil), "niltype()")
self.assertEqual(nil, nil)
self.assertNotEqual(nil, cons(1, nil))
self.assertNotEqual(cons(1, nil), nil)
with self.assertRaises(TypeError):
car(nil)
with self.assertRaises(TypeError):
cdr(nil)
self.assertEqual(list(nil), list())
self.assertEqual(tuple(nil), tuple())
def test_improper_cons(self):
z = cons(1, 2)
self.assertFalse(z.is_proper())
self.assertEqual(car(z), 1)
self.assertEqual(cdr(z), 2)
self.assertEqual(str(z), "(1 . 2)")