不同列表的断言错误

Question

I made a reverse enumerate without the use of the reversed() function. I want the string and the numbers to be printed in reverse. However, when testing, I get an AssertionError stating that the lists do not match.

def my_own_enumerate(a):
    for i in range(len(a)-1, -1, -1):
        return i, a[i]

class Test(unittest.TestCase):
    def test_my_own_enumerate(self):
        self.assertEqual([(0, "m"), (1, "e"), (2, "!")], list(my_own_enumerate("me!")))

Answer 1

• my_own_enumerate is meant to return a reversed enumeration (as you stated yourself) so I'm not sure why you assert its output with a non-reversed enumeration.

• The loop in my_own_enumerate returns after the first iteration, so it will always return only the last character and its index. Instead, try

  def my_own_enumerate(a): return [(i, a[i]) for i in range(len(a) - 1, -1, -1)]

Then

print(my_own_enumerate('me!'))
# [(2, '!'), (1, 'e'), (0, 'm')]

And

class Test(unittest.TestCase):
    def test_my_own_enumerate(self):
        self.assertEqual([(2, '!'), (1, 'e'), (0, 'm')], my_own_enumerate("me!"))

Does not fail.