django 学习笔记 （五）

五、Writing your first Django app, part 5

自动测试的好处

• 节省开发时间
• 避免错误
• 让别人能够接受你的代码，否则无法确认质量
• 帮助小组协同开发

第一个测试的例子

在前面的 polls 中有个小 bug ： Poll.was_published_recently()
在Poll的发布时间在未来的时候也返回 True

通过 admin页面可以很容易的验证，通过 Shell 也能够检测出这个bug。
python manage.py shell

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

1.写一个测试来暴露出这个bug

通常项目在建立的时候会自动建立一个模拟的tests.py文件，全部删除后改成这样。

import datetime

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

from polls.models import Poll

class PollMethodTests(TestCase):

    def test_was_published_recently_with_future_poll(self):
        """
        was_published_recently() should return False for polls whose
        pub_date is in the future
        """
        future_poll = Poll(pub_date=timezone.now() + datetime.timedelta(days=30))
        self.assertEqual(future_poll.was_published_recently(), False)

建立一个 django.test.TestCase 的子类 PollMethodTests , 在其中建立了一个测试方法 test_was_published_recently_with_future_poll() ，使用 assertEqual() 来验证。

2.运行测试

python manage.py test polls

测试的执行流程

• 在polls内寻找tests.py
• 寻找django.test.TestCase的子类
• 建立用于测试的数据库
• 寻找以 test开头的方法
• 建立实例
• 使用 assertEqual() 检测结果

3.修复 bug

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，通过

更复杂一点的测试

• 1天之内返回 True

• 超过1天返回 False

  def test_was_published_recently_with_old_poll(self):
      """
      was_published_recently() should return False for polls whose pub_date
      is older than 1 day
      """
      old_poll = Poll(pub_date=timezone.now() - datetime.timedelta(days=30))
      self.assertEqual(old_poll.was_published_recently(), False)
  
  def test_was_published_recently_with_recent_poll(self):
      """
      was_published_recently() should return True for polls whose pub_date
      is within the last day
      """
      recent_poll = Poll(pub_date=timezone.now() - datetime.timedelta(hours=1))
      self.assertEqual(recent_poll.was_published_recently(), True)
  

测试一个视图

通过工具来模拟web的行为

1.测试工具 client

• 建立测试环境

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

• 导入测试类

  >>> from django.test.client import Client
  >>> client = Client()
  

• 系列测试

  访问 / 返回404

      >>> response = client.get('/')
      >>> response.status_code
  

  使用reverse方法访问视图

      >>> from django.core.urlresolvers import reverse
      >>> response = client.get(reverse('polls:index'))
      >>> response.status_code
      >>> response.content
  

  访问 /polls/

      >>> from polls.models import Poll
      建立一个新Poll
          >>> from django.utils import timezone
          >>> p = Poll(question="Who is your favorite Beatle?", pub_date=timezone.now())
          >>> p.save()
      >>> response = client.get('/polls/')
      >>> response.content
      >>> response.context['latest_poll_list']
  

2.改进视图

不显示未来发表的Poll，修改 view.py 中的get_queryset() 方法.

from django.utils import timezone
...
def get_queryset(self):
    """
    Return the last five published polls (not including those set to be
    published in the future).
    """
    return Poll.objects.filter(
        pub_date__lte=timezone.now()
    ).order_by('-pub_date')[:5]

• 通过使用 __lte的方式来筛选记录

3.测试改进后的新视图

可以使用浏览器测试，也可以通过增加 tests.py的方式测试。

from django.core.urlresolvers import reverse

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

class PollViewTests(TestCase):
    def test_index_view_with_no_polls(self):
        """
        If no polls 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_poll_list'], [])

    def test_index_view_with_a_past_poll(self):
        """
        Polls with a pub_date in the past should be displayed on the index page.
        """
        create_poll(question="Past poll.", days=-30)
        response = self.client.get(reverse('polls:index'))
        self.assertQuerysetEqual(
            response.context['latest_poll_list'],
            ['<Poll: Past poll.>']
        )

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

    def test_index_view_with_future_poll_and_past_poll(self):
        """
        Even if both past and future polls exist, only past polls should be
        displayed.
        """
        create_poll(question="Past poll.", days=-30)
        create_poll(question="Future poll.", days=30)
        response = self.client.get(reverse('polls:index'))
        self.assertQuerysetEqual(
            response.context['latest_poll_list'],
            ['<Poll: Past poll.>']
        )

    def test_index_view_with_two_past_polls(self):
        """
        The polls index page may display multiple polls.
        """
        create_poll(question="Past poll 1.", days=-30)
        create_poll(question="Past poll 2.", days=-5)
        response = self.client.get(reverse('polls:index'))
        self.assertQuerysetEqual(
            response.context['latest_poll_list'],
             ['<Poll: Past poll 2.>', '<Poll: Past poll 1.>']
        )

• create_poll 用于构造数据

• 空Poll情况

  test_index_view_with_no_polls
  

• 正常显示过去的Poll

  test_index_view_with_a_past_poll
  

• 未来的不显示

  test_index_view_with_a_future_poll
  

• 过去未来同时存在，只显示过去

  test_index_view_with_future_poll_and_past_poll
  

• 显示多个polls

  test_index_view_with_two_past_polls
  

4.测试 DetailView

防止猜测来直接访问未来的poll

修改 DetailView方法

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

增加测试

• 访问未来的poll test_detail_view_with_a_future_poll

• 访问过去的poll test_detail_view_with_a_past_poll

  class PollIndexDetailTests(TestCase):
      def test_detail_view_with_a_future_poll(self):
          """
          The detail view of a poll with a pub_date in the future should
          return a 404 not found.
          """
          future_poll = create_poll(question='Future poll.', days=5)
          response = self.client.get(reverse('polls:detail', args=(future_poll.id,)))
          self.assertEqual(response.status_code, 404)
  
      def test_detail_view_with_a_past_poll(self):
          """
          The detail view of a poll with a pub_date in the past should display
          the poll's question.
          """
          past_poll = create_poll(question='Past Poll.', days=-5)
          response = self.client.get(reverse('polls:detail', args=(past_poll.id,)))
          self.assertContains(response, past_poll.question, status_code=200)
  

如果设置 handler404, 状态返回始终是 200, 测试未来的始终报错

测试的原则

• 测试的名字包含功能的描述
• 每个测试条件一个测试方法
• 每个 Model 或者 view 一个测试类