同样的Django单元测试有时失败，有时成功

Question

我有以下Django单元测试：

def test_highscores_no_n_success_(self):
    """Checks that top 10 highscores of an owner are returned,
    if no number of highscores is specified in the request"""
    high_score = 100
    for users in range(15):
        user = create_user(1, 1, "aguha")
        user.high_score = high_score
        user.save()
        high_score +=10
    response = self.client.get('/api/highscores/', 
                                {'token': 1, 'key': 1})
    self.assertContains(response, 
                        "\"id\": 10, \"high_score\": 180")

对于以下函数：

def highscores(request):
    """Returns the top n (or 10) high scores for an owner"""
    r = request.GET
    token = r['token']
    owner = Owner.objects.get(api_token=token)
    try:
        n = r['n']
    except KeyError:
        user_count = User.objects.filter(owner=owner).count()
        if user_count >= 10:
            n = 10
        else:
            n = user_count
    top_scorers = User.objects.filter(owner=owner).order_by('-high_score').values('id', 'high_score')[:n]
    top_scorers_json = json.dumps(list(top_scorers))
    return HttpResponse(top_scorers_json,
                    content_type="application/json")

这是create_user函数：

def create_user(token, key, owner_username):
    """Creates a user object for the purpose of testing"""
    try:
        owner = Owner.objects.get(api_token=token)
    except ObjectDoesNotExist:
        owner = Owner.objects.create(api_token=token, api_key=key, 
                                    username=owner_username)
    return User.objects.create(owner=owner)

奇怪的是，这个测试有时成功，有时失败。如果失败，它会说在响应中找不到"id": 10, "high_score": 180。这怎麽可能？每次新的测试都会重置数据库，并在测试完成后擦除数据库，所以这应该不是问题。这里有什么问题？

我最初的假设是，这可能与运行测试之间的时间有关。但这似乎没有什么效果。我可以一个接一个地运行它几次，它就能正常工作。然后我回来并在几分钟后运行，它失败了。是我的函数有问题还是我的测试有问题？

Answer 1

我弄明白了为什么我会得到这个错误。在返回的列表中，有时id出现在high_score之前，即我得到的是"id": 10, "high_score": 180，这就是测试运行正常的原因。但在其他时候，high_score出现在id之前，即它是"high_score": 180, "id": 10，这就是测试失败的原因。