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python - 为什么 unittest 不认为这两个列表是相等的？

问题描述

所以我只是在实践中实现了一些经典的排序算法，并想出了这个合并排序的解决方案：

def merge_sort(numbers):
'''Sorts a list based on the traditional merge-sort'''

    if len(numbers) <= 1:
        return numbers

    result = []

    mid = len(numbers) // 2

    left = merge_sort(numbers[mid:])
    right = merge_sort(numbers[:mid])

    l_idx = 0
    r_idx = 0

    # compare all numbers in the two lists
    while l_idx < len(left) and r_idx < len(right):
        if left[l_idx] > right[r_idx]:
            result.append(right[r_idx])
            r_idx += 1
        else:
            result.append(left[l_idx])
            l_idx += 1

    # make sure leftover numbers are added to result
    result += left[l_idx:]
    result += right[r_idx:]

    return result

它似乎有效，例如：

>> number_list = [1, 3, 7, 8, 12, 23, 41, 3, 7, 12, 41, 24, 29]
>> sorted(number_list)
[1, 3, 3, 7, 7, 8, 12, 12, 23, 24, 29, 41, 41]
>> merge_sort(number_list)
[1, 3, 3, 7, 7, 8, 12, 12, 23, 24, 29, 41, 41]

输出是正确的并且排序正确但是当我运行我的单元测试时，它看起来像这样：

import sorting as s
import unittest
import random
unsorted_list = [random.randint(1, 120) for _ in range(100)]
expected_sorted_list = sorted(unsorted_list)

    def test_mergesort(self):

        merge_sorted_list = s.merge_sort(unsorted_list)
        self.assertEqual(expected_sorted_list, merge_sorted_list)

然后当我运行时：

>> python -m unittest test_sorting
AssertionError: Lists differ: [4, 4[42 chars]2, 13, 14, 15, 15, 16, 17, 18, 19, 20, 21, 22,[308 chars] 120] != [4, 4[42 chars]2, 13]

First list contains 84 additional elements.
First extra element 16:
14

Diff is 762 characters long. Set self.maxDiff to None to see it.

----------------------------------------------------------------------
Ran 2 tests in 0.002s

FAILED (failures=1)

为什么我的单元测试会引发错误？即使我已经测试了合并排序功能，它似乎排序正确。

目录结构：

/classical-algorithms
    sorting.py
    test_sorting.py

标签： pythonunit-testing

解决方案

让包含测试的 python 文件成为test_sorting.py.

然后以下对我有用：

import sorting as s
import unittest
import random
unsorted_list = [random.randint(1, 120) for _ in range(100)]
expected_sorted_list = sorted(unsorted_list)

class tests(unittest.TestCase):
    def test_mergesort(self):
        merge_sorted_list = s.merge_sort(unsorted_list)
        self.assertEqual(expected_sorted_list, merge_sorted_list)

运行测试：

$python -m unittest test_sorting
.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK

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