参考资料：Tutorial05
Introducing automated testing
自动化测试：
- 测试可以节省你的时间
- 测试不仅仅可以发现问题，还能防止问题
- 测试使你的代码更受欢迎
- 测试有助于团队合作
Writing our first test
1. identify a bug
onfirm the bug by using the shell to check the method on a question whose date lies in the future:
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| $ python manage.py shell
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| >>> 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
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2. create a test to expose the bug
通常，我们会把测试代码放在应用的tests.py文件中，测试系统将自动地从任何名字以test开头的文件中查找测试程序。每个app在创建的时候，都会自动创建一个tests.py文件，就像views.py等文件一样。
将下面的代码输入投票应用的polls/tests.py文件中：
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| 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):
"""
在将来发布的问卷应该返回False
"""
time = timezone.now() + datetime.timedelta(days=30)
future_question = Question(pub_date=time)
self.assertIs(future_question.was_published_recently(), False)
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我们在这里创建了一个django.test.TestCase的子类，它具有一个方法，该方法创建一个pub_date在未来的Question实例。最后我们检查was_published_recently()的输出，它应该是 False。
3. Running tests
在终端中，运行下面的命令，
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| $ python manage.py test polls
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你将看到结果如下：
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| Creating test database for alias 'default'...
F
======================================================================
FAIL: test_was_published_recently_with_future_question (polls.tests.QuestionMethodTests)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/path/to/mysite/polls/tests.py", line 16, in test_was_published_recently_with_future_question
self.assertIs(future_question.was_published_recently(), False)
AssertionError: True is not False
----------------------------------------------------------------------
Ran 1 test in 0.001s
FAILED (failures=1)
Destroying test database for alias 'default'...
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这其中都发生了些什么？：
python manage.py test polls 命令会查找 polls 应用中所有的测试程序- 发现一个
django.test.TestCase 的子类 - 为测试创建一个专用的数据库
- 查找名字以
test 开头的测试方法 - 在
test_was_published_recently_with_future_question 方法中，创建一个 Question 实例，该实例的 pub_data 字段的值是30天后的未来日期。 - 然后利用
assertIs() 方法，它发现 was_published_recently() 返回了True，而不是我们希望的 False。
最后，测试程序会通知我们哪个测试失败了，错误出现在哪一行。
整个测试用例基本上和 Python 内置的 unittest 非常相似，大家可以参考 Python 教程中测试相关的章节。
4. Fix the bug
修改源代码，具体如下：
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| # polls/models.py
def was_published_recently(self):
now = timezone.now()
return now - datetime.timedelta(days=1) <= self.pub_date <= now
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再次运行测试程序：
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| $ python manage.py test polls
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| Creating test database for alias 'default'...
.
----------------------------------------------------------------------
Ran 1 test in 0.001s
OK
Destroying test database for alias 'default'...
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可以看到 bug 已经没有了。
5. More comprehensive tests
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| def test_was_published_recently_with_old_question(self):
"""
was_published_recently() returns False for questions whose pub_date
is older than 1 day.
"""
time = timezone.now() - datetime.timedelta(days=1, seconds=1)
old_question = Question(pub_date=time)
self.assertIs(old_question.was_published_recently(), False)
def test_was_published_recently_with_recent_question(self):
"""
was_published_recently() returns True for questions whose pub_date
is within the last day.
"""
time = timezone.now() - datetime.timedelta(hours=23, minutes=59, seconds=59)
recent_question = Question(pub_date=time)
self.assertIs(recent_question.was_published_recently(), True)
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Test a view
The Django test client
Django provides a test Client to simulate a user interacting with the code at the view level. We can use it in tests.py or even in the shell.
We will start again with the shell, where we need to do a couple of things that won’t be necessary in tests.py. The first is to set up the test environment in the shell:
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| $ python manage.py shell
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| >>> from django.test.utils import setup_test_environment
>>> setup_test_environment()
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setup_test_environment() installs a template renderer which will allow us to examine some additional attributes on responses such as response.context that otherwise wouldn’t be available.
Next we need to import the test client class:
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| >>> from django.test import Client
>>> # create an instance of the client for our use
>>> client = Client()
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With that ready, we can ask the client to do some work for us:
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| >>> # get a response from '/'
>>> response = client.get('/')
Not Found: /
>>> # we should expect a 404 from that address; if you instead see an
>>> # "Invalid HTTP_HOST header" error and a 400 response, you probably
>>> # omitted the setup_test_environment() call described earlier.
>>> 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.urls import reverse
>>> response = client.get(reverse('polls:index'))
>>> response.status_code
200
>>> response.content
b'\n <ul>\n \n <li><a href="/polls/1/">What's up?</a></li>\n \n </ul>\n\n'
>>> response.context['latest_question_list']
<QuerySet [<Question: What's up?>]>
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Improving our view
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| # polls/views.py
from django.utils import timezone
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 (not including those set to be
published in the future).
"""
return Question.objects.filter(
pub_date__lte=timezone.now()
).order_by('-pub_date')[:5]
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Test our new view
Add the following to polls/tests.py:
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| from django.urls import reverse
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and we’ll create a shortcut function to create questions as well as a new test class:
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| def create_question(question_text, days):
"""
Create a question with the given `question_text` and 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 QuestionIndexViewTests(TestCase):
def test_no_questions(self):
"""
If no questions exist, an appropriate message is 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_past_question(self):
"""
Questions with a pub_date in the past are 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_future_question(self):
"""
Questions with a pub_date in the future aren't 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.")
self.assertQuerysetEqual(response.context['latest_question_list'], [])
def test_future_question_and_past_question(self):
"""
Even if both past and future questions exist, only past questions
are 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_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.>']
)
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Testing the DetailView
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| # 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())
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And of course, we will add some tests, to check that a Question whose pub_date is in the past can be displayed, and that one with a pub_date in the future is not:
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| # polls/tests.py
class QuestionDetailViewTests(TestCase):
def test_future_question(self):
"""
The detail view of a question with a pub_date in the future
returns a 404 not found.
"""
future_question = create_question(question_text='Future question.', days=5)
url = reverse('polls:detail', args=(future_question.id,))
response = self.client.get(url)
self.assertEqual(response.status_code, 404)
def test_past_question(self):
"""
The detail view of a question with a pub_date in the past
displays the question's text.
"""
past_question = create_question(question_text='Past Question.', days=-5)
url = reverse('polls:detail', args=(past_question.id,))
response = self.client.get(url)
self.assertContains(response, past_question.question_text)
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