[英]How do I prevent Django from running unit tests on parent class when subclassing TestCase?
Background: I am working on a web scraper to track prices at online stores.背景:我正在开发一个网络爬虫来跟踪在线商店的价格。 It uses Django.
它使用 Django。 I have a module for each store, with functions like
get_price()
and get_product_name()
written for each one, so that the modules can be used interchangeably by the main scraper module.我为每个商店都有一个模块,为每个商店编写了诸如
get_price()
和get_product_name()
类的函数,以便主刮板模块可以互换使用这些模块。 I have store_a.py, store_b.py, store_c.py, et cetera, each with these functions defined.我有 store_a.py、store_b.py、store_c.py 等等,每个都定义了这些函数。
In order to prevent duplication of code, I've made StoreTestCase, which inherits from TestCase.为了防止代码重复,我制作了 StoreTestCase,它继承自 TestCase。 For each store, I have a subclass of StoreTestCase, like StoreATestCase and StoreBTestCase.
对于每个商店,我都有一个 StoreTestCase 的子类,例如 StoreATestCase 和 StoreBTestCase。
When I manually test the StoreATestCase class , the test runner does what I want.当我手动测试 StoreATestCase类时,测试运行器会执行我想要的操作。 It uses the data in the child class
self.data
for its tests, and doesn't attempt to set up and test the parent class on its own:它使用子类
self.data
的数据进行测试,并且不会尝试自行设置和测试父类:
python manage.py test myproject.tests.test_store_a.StoreATest
However, when I manually test against the module , like:但是,当我手动测试模块时,例如:
python manage.py test myproject.tests.test_store_a
It first runs the tests for the child class and succeeds, but then it runs them for the parent class and returns the following error:它首先为子类运行测试并成功,但随后为父类运行它们并返回以下错误:
for page in self.data:
TypeError: 'NoneType' object is not iterable
store_test.py (parent class) store_test.py (父类)
from django.test import TestCase
class StoreTestCase(TestCase):
def setUp(self):
'''This should never execute but it does when I test test_store_a'''
self.data = None
def test_get_price(self):
for page in self.data:
self.assertEqual(store_a.get_price(page['url']), page['expected_price'])
test_store_a.py (child class) test_store_a.py (子类)
import store_a
from store_test import StoreTestCase
class StoreATestCase(StoreTestCase):
def setUp(self):
self.data = [{'url': 'http://www.foo.com/bar', 'expected_price': 7.99},
{'url': 'http://www.foo.com/baz', 'expected_price': 12.67}]
How do I ensure the Django test runner only tests the child class, and not the parent class?我如何确保 Django 测试运行器只测试子类,而不是父类?
One way to fix this is to use Mixins
:解决此问题的一种方法是使用
Mixins
:
from django.test import TestCase
class StoreTestCase(object):
def setUp(self):
'''This should never execute but it does when I test test_store_a'''
self.data = None
def test_get_price(self):
for page in self.data:
self.assertEqual(store_a.get_price(page['url']), page['expected_price'])
class StoreATestCase(StoreTestCase, TestCase):
def setUp(self):
self.data = [{'url': 'http://www.foo.com/bar', 'expected_price': 7.99},
{'url': 'http://www.foo.com/baz', 'expected_price': 12.67}]
The StoreTestCase
will not be executed since it is not a TestCase
, but your StoreATestCase
will still benefit from the inheritance. StoreTestCase
不会被执行,因为它不是一个TestCase
,但你的StoreATestCase
仍然会从继承中受益。
I think that your issue happens because StoreTestCase
is a TestCase
instance, so it gets executed when you run the tests.我认为你的问题发生是因为
StoreTestCase
是一个TestCase
实例,所以当你运行测试时它会被执行。
Edit:编辑:
I would also suggest to raise an exception in StoreTestCase.setUp
, explicitly saying that is not implemented.我还建议在
StoreTestCase.setUp
引发异常,明确表示未实现。 Have a look at these exception .看看这些异常。 You would end up with something like this:
你最终会得到这样的结果:
import exceptions # At the top of the file
[...]
def setUp(object):
raise exceptions.NotImplementedError('Please override this method in your subclass')
You can to hide base class inside another:您可以将基类隐藏在另一个中:
store_test.py (parent class) store_test.py (父类)
from django.test import TestCase
class TestHelpers(object):
class StoreTestCase(TestCase):
...
test_store_a.py (child class) test_store_a.py (子类)
import store_a
from store_test import TestHelpers
class StoreATestCase(TestHelpers.StoreTestCase):
...
If you want to avoid the Multi-inheritance, this is a possible solution as well.如果您想避免多重继承,这也是一个可能的解决方案。 Django Test Cases are not called via the init constructor so the setUp Method has to be overridden:
Django 测试用例不是通过init构造函数调用的,因此必须覆盖 setUp 方法:
from unittest import SkipTest
from django.test import TestCase
class BaseTest(TestCase):
def setUp(self):
if self.__class__ == BaseTest:
raise SkipTest('Abstract test')
your_stuff = 'here'
...
The only downside is, that the skipped test will be mentioned in your test report.唯一的缺点是,您的测试报告中会提到跳过的测试。 Unittest documentation: https://docs.python.org/dev/library/unittest.html#unittest.SkipTest
单元测试文档: https ://docs.python.org/dev/library/unittest.html#unittest.SkipTest
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