如何在 Python 中生成动态(参数化)单元测试? [英] How do you generate dynamic (parameterized) unit tests in Python?

问题描述

我有某种测试数据，想为每个项目创建一个单元测试.我的第一个想法是这样做:

I have some kind of test data and want to create a unit test for each item. My first idea was to do it like this:

import unittest

l = [["foo", "a", "a",], ["bar", "a", "b"], ["lee", "b", "b"]]

class TestSequence(unittest.TestCase):
    def testsample(self):
        for name, a,b in l:
            print "test", name
            self.assertEqual(a,b)

if __name__ == '__main__':
    unittest.main()

这样做的缺点是它可以在一次测试中处理所有数据.我想为每个项目即时生成一个测试.有什么建议吗?

The downside of this is that it handles all data in one test. I would like to generate one test for each item on the fly. Any suggestions?

推荐答案

这称为参数化".

有多种工具支持这种方法.例如:

There are several tools that support this approach. E.g.:

• pytest 的装饰器
• 参数化

生成的代码如下所示:

from parameterized import parameterized

class TestSequence(unittest.TestCase):
    @parameterized.expand([
        ["foo", "a", "a",],
        ["bar", "a", "b"],
        ["lee", "b", "b"],
    ])
    def test_sequence(self, name, a, b):
        self.assertEqual(a,b)

哪个将生成测试:

test_sequence_0_foo (__main__.TestSequence) ... ok
test_sequence_1_bar (__main__.TestSequence) ... FAIL
test_sequence_2_lee (__main__.TestSequence) ... ok

======================================================================
FAIL: test_sequence_1_bar (__main__.TestSequence)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/site-packages/parameterized/parameterized.py", line 233, in <lambda>
    standalone_func = lambda *a: func(*(a + p.args), **p.kwargs)
  File "x.py", line 12, in test_sequence
    self.assertEqual(a,b)
AssertionError: 'a' != 'b'

由于历史原因，我将保留大约 2008 年的原始答案):

For historical reasons I'll leave the original answer circa 2008):

我使用这样的东西:

import unittest

l = [["foo", "a", "a",], ["bar", "a", "b"], ["lee", "b", "b"]]

class TestSequense(unittest.TestCase):
    pass

def test_generator(a, b):
    def test(self):
        self.assertEqual(a,b)
    return test

if __name__ == '__main__':
    for t in l:
        test_name = 'test_%s' % t[0]
        test = test_generator(t[1], t[2])
        setattr(TestSequense, test_name, test)
    unittest.main()

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