Question

我正在尝试通过对unittest.testcase类进行子类化来创建自定义单元测试框架，但在处理__init__方法时似乎犯了错误。

我无法弄清楚为什么ComplexTest的构造函数不会在BasicTest中的构造函数之前被调用，并且异常似乎也与我的构造函数有关。

我对Python很陌生，所以对于如何解决这个特定问题或者我的用例的替代架构的任何帮助都是非常受欢迎的。

谢谢！

1）test_framework.py

import unittest

class BasicTest(unittest.TestCase):
    def __init__(self, *args, **kwargs):
        print('BasicTest.__init__')
        super(unittest.TestCase, self).__init__(*args, **kwargs)

    def setUp(self):
        print('BasicTest.setUp')
        super(unittest.TestCase, self).tearDown()

    def tearDown(self):
        print('BasicTest.tearDown')
        super(unittest.TestCase, self).tearDown()


class ComplexTest(BasicTest):
    def __init__(self, *args, **kwargs):
        print('ComplexTest.__init__')
        super(BasicTest, self).__init__(*args, **kwargs)

    def setUp(self):
        print('ComplexTest.setUp')
        super(BasicTest, self).tearDown()

    def tearDown(self):
        print('ComplexTest.tearDown')
        super(BasicTest, self).tearDown()

2）test.py

import unittest
import test_framework

class TestValueFunctions(test_framework.ComplexTest):
    def __init__(self, *args, **kwargs):
        print('TestValueFunctions.__init__')
        super(test_framework.ComplexTest, self).__init__(*args, **kwargs)

    def setUp(self):
        print('TestValueFunctions.setUp')
        super(test_framework.ComplexTest, self).tearDown()
        self.value = 4711

    def tearDown(self):
        print('TestValueFunctions.tearDown')
        super(test_framework.ComplexTest, self).tearDown()

    def test_value(self):
        print('TestValueFunctions.test_value')
        self.assertEqual(self.value, 4711)

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

3）现在尝试运行此功能时，我会看到以下堆栈

TestValueFunctions.__init__
BasicTest.__init__
Traceback (most recent call last):
  File "D:\MyDev\ljs_app\trunk\examples\python\unittest\test.py", line 23, in <module>
    unittest.main()
  File "C:\Python27\lib\unittest\main.py", line 94, in __init__
    self.parseArgs(argv)
  File "C:\Python27\lib\unittest\main.py", line 149, in parseArgs
    self.createTests()
  File "C:\Python27\lib\unittest\main.py", line 155, in createTests
    self.test = self.testLoader.loadTestsFromModule(self.module)
  File "C:\Python27\lib\unittest\loader.py", line 65, in loadTestsFromModule
    tests.append(self.loadTestsFromTestCase(obj))
  File "C:\Python27\lib\unittest\loader.py", line 56, in loadTestsFromTestCase
    loaded_suite = self.suiteClass(map(testCaseClass, testCaseNames))
  File "D:\MyDev\ljs_app\trunk\examples\python\unittest\test.py", line 7, in __init__
    super(test_framework.ComplexTest, self).__init__(*args, **kwargs)
  File "D:\MyDev\ljs_app\trunk\examples\python\unittest\test_framework.py", line 6, in __init__
    super(unittest.TestCase, self).__init__(*args, **kwargs)
TypeError: object.__init__() takes no parameters

Answer 1

确实你的init方法错了。

class BasicTest(unittest.TestCase):
    def __init__(self, *args, **kwargs):
        print('BasicTest.__init__')
        super(unittest.TestCase, self).__init__(*args, **kwargs)

应该是：

class BasicTest(unittest.TestCase):
    def __init__(self, *args, **kwargs):
        print('BasicTest.__init__')
        super(BasicTest, self).__init__(*args, **kwargs)

这将在BasicTest的母类（TestCase）上调用__init__。这与setUp和tearDown相同：

class BasicTest(unittest.TestCase):
    ...
    def setUp(self):
        print('BasicTest.setUp')
        super(BasicTest, self).setUp()

Answer 2

啊super！谁知道它为什么做任何事情。如果您在测试中停止使用它，而是显式调用您想要的父类，如下所示：

class BasicTest(unittest.TestCase):
    def __init__(self, *args, **kwargs):
        print('BasicTest.__init__')
        unittest.TestCase.__init__(self, *args, **kwargs)

您最终会得到以下输出：

TestValueFunctions.__init__
ComplexTest.__init__
TestValueFunctions.setUp
ComplexTest.setUp
TestValueFunctions.test_value
TestValueFunctions.tearDown
ComplexTest.tearDown
.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK

请参阅：Python's Super is nifty, but you can't use it

在python中重载unittest.testcase

2 个答案: