Py.test:从类中参数化测试用例 [英] Py.test: parametrize test cases from classes

问题描述

我目前正在关注这个 py.test 示例，当我不这样做时它会起作用使用类，但是当我将测试用例引入类时，我失败了.

I'm currently following this py.test example and it works out when I do not use classes, however when I introduce test cases into classes I am failing.

我设法编写的最小案例如下:

The smallest case I managed to write is the following:

import unittest

import pytest

class FixtureTestCase(unittest.TestCase):

    @pytest.mark.parametrize("test_input,expected", [
    ("3+5", 8),
    ("2+4", 6),
    ("6*9", 42),
    ])
    def test_1(self, a, b):
        self.assertEqual(a, b)

不幸的是当我执行

  py.test  test_suite.py

我收到错误消息:

  TypeError: test_1() takes exactly 3 arguments (1 given)

我该怎么做才能生成一组 test_1 测试?

How can I do in order to generate a battery of test_1 tests?

推荐答案

如果你从 unittest.TestCase 子类化，你的测试方法不能有额外的参数.如果您只是从 object 子类化，它会起作用(尽管您必须使用常规的 assert 语句而不是 TestCase.assertEqual 方法.

If you subclass from unittest.TestCase, your test methods cannot have additional arguments. If you simply subclass from object, it will work (though you'll have to use regular assert statements instead of the TestCase.assertEqual methods.

import unittest

import pytest

class TestCase(object):

    @pytest.mark.parametrize("test_input,expected", [
    ("3+5", 8),
    ("2+4", 6),
    ("6*9", 42),
    ])
    def test_1(self, a, b):
        assert eval(a) == b

不过，在这一点上，它有点回避了为什么要使用类而不只是定义函数的问题，因为测试本质上是相同的，但需要较少的整体样板和代码.

At that point though, it kind of begs the question why you're using classes instead of just defining functions, since the test will essentially be the same, but require less overall boilerplate and code.

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