writing_first_django_app_part5
Automated Testing
解决问题一个很好的方法是首先描述这个问题，然后写出代码来实现它。但是很多人习惯先写好代码然后再进行调试找问题。也许在写代码之前先写好一些测试会是更好的选择。
A little bug
前面在我们的Question.was_published_recently()函数中有一个小问题，如果它是一天之内创建的则会返回True，但是如果pub_date是未来的时间也会返回True
通常应用的测试会放到tests.py文件中，现在在polls/tests.py里添加测试：
import datetime
from django.utils import timezone
from django.test import TestCase
from polls.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(pub_date=time)
self.assertEqual(future_question.was_published_recently(), False)
这个测试类是继承于TestCase类，它创建了一个将来时间的Question，然后self.assertEqual()函数是测试函数的返回结果，正确应该返回False
运行这个测试:
$ python manage.py test polls
得到如下结果：
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.assertEqual(future_question.was_published_recently(), False)
AssertionError: True != False
----------------------------------------------------------------------
Ran 1 test in 0.001s
FAILED (failures=1)
Destroying test database for alias 'default'...
首先test polls会在polls应用下查找测试，然后找到TestCase类的子类，就会创建一个特定的数据库来进行测试。测试类中测试的函数会以'test'开头，即上面的test_was published_...，最后就是运行assertEqual函数看结果是否与预想的一致，上面的结果是FAILED
修正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：
Creating test database for alias 'default'... . ---------------------------------------------------------------------- Ran 1 test in 0.001s OK Destroying test database for alias 'default'...
测试异常的情况之后，还要加上一个正确的例子，函数应该返回True:
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)
Test a view
Django提供一个测试Client来模拟一个用户在view测层面与代码进行交互。可以通过tests.py或者shell来进行。
用shell来测试：
# 设置测试环境
>>> from django.test.utils import setup_test_environment
>>> setup_test_environment()
# 建立一个client来进行测试
>>> from django.test import Client
>>> # create an instance of the client for our use
>>> client = Client()
# 一些测试用例
>>> # 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 if 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?>]
前面我们使用了generic.ListView来创建view，如下：
# 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]
最后返回Question并没有对时间在现在之后的进行筛选，我们作出修改：
from django.utils import timezone
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]
filter(pub_date__lte=timezone.now()返回时间早于或者等于now的Questions
Testing the view
在tests.py中添加对index的测试：
from django.core.urlresolvers import reverse
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'], [])
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.>']
)
首先为了方便在测试的时候创建question，先定义函数create_question. 下面几个函数分别对几个情况进行测试，注意函数命名要体现测试的内容。
Test DetailView
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())
# 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)
上面就是一些测试的例子，测试代码可能看起来很多，但其实它们都是非常有用的。When testing, more is better