Django入门笔记【五】

入门笔记翻译整理自：https://docs.djangoproject.com/en/1.8/

*该笔记将使用一个关于投票网络应用（poll application）的例子来阐述Django的用法。

*自动测试（automated testing）

1. 首个测试

Question.was_published_recently()方法中有一个小问题，它会将未来的时间也显示为昨日发布。

使用shell来测试：

>>> import datetime
>>> from django.utils import timezone
>>> from polls.models import Question
>>> # create a Question instance with pub_date 30 days in the future
>>> future_question = Question(pub_date=timezone.now() + datetime.timedelta(days=30))
>>> # was it published recently?
>>> future_question.was_published_recently()
True

2. 创建测试

测试系统会自动寻找任何以test开头的文件。在polls里创建tests.py：

# polls/tests.py

import datetime

from django.utils import timezone
from django.test import TestCase

from .models import Question

class QuestionMethodTests(TestCase):
    
    def test_was_published_recently_with_future_question(self):
        """
        was_published_recently should return False for questions whose     
        pub_date is in the future.
        """
        time = timezone.now() + datetime.timedelta(days=30)
        future_question = Question(pubdate=time)
        self.assertEqual(future_question.was_published_recently(), False)

3. 运行测试 

运行代码 $ python manage.py test polls 

4. 订正错误

# polls/models.py

def was_published_recently(self):
    now = timezone.now()
    return now - datetime.timedelta(days=1) <= self.pub_date <= now

再次运行测试

5. 更复杂的测试

为了防止订正带来更多的错误，添加代码：

# polls/tests.py

def test_was_published_recently_with_old_question(self):
    """
    was_published_recently() should return False for questions whose 
    pub_date is older than 1 day.
    """
    time = timezone.now() - datetime.timedelta(days=30)
    old_question = Question(pub_date=time)
    self.assertEqual(old_question.was_published_recently(), False)

def test_was_published_recently_with_recent_question(self):
    """
    was_published_recently() should return True for questions whose
    pub_date is within the last day.
    """
    time = timezone.now() - datetime.timedelta(hours=1)
    recent_question = Question(pub_date=time)
    self.assertEqual(recent_question.was_published_recently(), True)

6. 测试视图（Test a view）

Django提供了测试Client来模拟用户和视图的交互。我们可以在test.py或者shell中使用它。

先来看shell，初始化环境：

>>> from django.test.utils import setup_test_environment
>>> setup_test_environment()

再来导入Client：

>>> from django.test import Client
>>> # create an instance of the client for our use
>>> client = Client()

 接下来：

>>> # get a response from '/'
>>> response = client.get('/')
>>> # we should expect a 404 from that address
>>> response.status_code
404
>>> # on the other hand we should expect to find something at '/polls/'
>>> # we'll use 'reverse()' rather than a hardcoded URL
>>> from django.core.urlresolvers import reverse
>>> response = client.get(reverse('polls: index'))
>>> response.status_code
200
>>> response.content
'


    <p>No polls are available.</p>

'
>>> #note - you might get unexpected results of your ``TIME_ZONE``
>>> # in ``settings.py`` is not correct. If you need to change it,
>>> # you will also need to restart your shell session
>>> from polls.models import Question
>>> from django.utils import timezone
>>> # create a Question and save it
>>> q = Question(question_text="Who is your favorite Beatle?", pub_date=timezone.now())
>>> q.save()
>>> # check the response once again
>>> response = client.get('/polls/')
>>> response.content
'


    <ul>
    
        <li><a href="/polls/1/">Who is your favorite Beatle?</a>
</li>
    
    </ul>

'
>>> # If the following doesn't work, you probably omitted the call to
>>> # setup_test_environment() described above
>>> response.context['latest_question_list']
[<Question: Who is your favorite Beatle?>]

将视图

# polls/views.py

class IndexView(generic.ListView):
    template_name = 'polls/index.html'
    context_object_name = 'latest_question_list'
    
    def get_queryset(self):
        """Return the last five published questions."""
        return Question.objects.order_by('-pub_date')[:5]

改进为：

# polls/views.py
from django.utils import timezone
# 同时修改get_queryset方法
def get_queryset(self):
    """
    Return the last five published questions (not including those set to
    be published in the future).
    """
    return Question.objects.filter(
        pub_date_lte=timezone.now()
    ).order_by('-pub_date')[:5]

接下来，基于之前在Shell里做的，我们来创建一个test文件：

# polls/tests.py

def create_question(question_text, days):
    """
    Creates a question with the given `question_text` published the given
    number of `days` offset to now (negative for questions published
    in the past, positive for questions that have yet to be published).
    """
    time = timezone.now() + datetime.timedelta(days=days)
    return Question.objects.create(question_text=question_text,
                                   pub_date=time)


class QuestionViewTests(TestCase):
    def test_index_view_with_no_questions(self):
        """
        If no questions exist, an appropriate message should be displayed.
        """
        response = self.client.get(reverse('polls:index'))
        self.assertEqual(response.status_code, 200)
        self.assertContains(response, "No polls are available.")
        self.assertQuerysetEqual(response.context['latest_question_list'], [])

    def test_index_view_with_a_past_question(self):
        """
        Questions with a pub_date in the past should be displayed on the
        index page.
        """
        create_question(question_text="Past question.", days=-30)
        response = self.client.get(reverse('polls:index'))
        self.assertQuerysetEqual(
            response.context['latest_question_list'],
            ['<Question: Past question.>']
        )

    def test_index_view_with_a_future_question(self):
        """
        Questions with a pub_date in the future should not be displayed on
        the index page.
        """
        create_question(question_text="Future question.", days=30)
        response = self.client.get(reverse('polls:index'))
        self.assertContains(response, "No polls are available.",
                            status_code=200)
        self.assertQuerysetEqual(response.context['latest_question_list'], [])

    def test_index_view_with_future_question_and_past_question(self):
        """
        Even if both past and future questions exist, only past questions
        should be displayed.
        """
        create_question(question_text="Past question.", days=-30)
        create_question(question_text="Future question.", days=30)
        response = self.client.get(reverse('polls:index'))
        self.assertQuerysetEqual(
            response.context['latest_question_list'],
            ['<Question: Past question.>']
        )

    def test_index_view_with_two_past_questions(self):
        """
        The questions index page may display multiple questions.
        """
        create_question(question_text="Past question 1.", days=-30)
        create_question(question_text="Past question 2.", days=-5)
        response = self.client.get(reverse('polls:index'))
        self.assertQuerysetEqual(
            response.context['latest_question_list'],
            ['<Question: Past question 2.>', '<Question: Past question 1.>']
        )

到目前为止，还不错。但是，如果用户仍然可以通过猜测，来进入未来的问题中，因此我们对DetailView也做相应改变：

# polls/views.py

class DetailView(generic.DetailView):
    ...
    def get_queryset(self):
        """
        Excludes any questions that aren't published yet.
        """
        return Question.objects.filter(pub_date__lte=timezone.now())

接下来，对此进行测试：

# polls/tests.py

class QuestionIndexDetailTests(TestCase):
    def test_detail_view_with_a_future_question(self):
        """
        The detail view of a question with a pub_date in the future should
        return a 404 not found.
        """
        future_question = create_question(question_text='Future question.',
                                          days=5)
        response = self.client.get(reverse('polls:detail',
                                   args=(future_question.id,)))
        self.assertEqual(response.status_code, 404)

    def test_detail_view_with_a_past_question(self):
        """
        The detail view of a question with a pub_date in the past should
        display the question's text.
        """
        past_question = create_question(question_text='Past Question.',
                                        days=-5)
        response = self.client.get(reverse('polls:detail',
                                   args=(past_question.id,)))
        self.assertContains(response, past_question.question_text,
                            status_code=200)

-- The End --