python - 使用unittest时如何自由组合多个setUp()/tearDown()基类？

Question

有多种设置:创建应用程序驱动程序、创建虚拟设备、进行登录。

一些测试用例只需要应用程序驱动程序，一些需要应用程序驱动程序和登录，一些需要应用程序驱动程序和设备，其他测试用例使用所有三个。

如何制作类似 Combine<Ts...> 的东西模板:

#include <iostream>

// The unittest.TestCase.
struct TestCase
{
    virtual void setUp() {}
    virtual void tearDown() {}
};

template <typename ...Ts>
struct Combine: public TestCase, public Ts...
{
    virtual void setUp() override { int t[] = { 0, (Ts::setUp(), 1)... }; }

    // TODO: invert the order
    virtual void tearDown() override { int t[] = { 0, (Ts::tearDown(), 1)... }; }
};

// Setups for 'login' only.
struct Login
{
    void setUp() { std::cout << "Login setup" << std::endl; }
    void tearDown() { std::cout << "Login teardown" << std::endl; }
};

// Setups for 'device' only.
struct Device
{
    void setUp() { std::cout << "Device setup" << std::endl; }
    void tearDown() { std::cout << "Device teardown" << std::endl; }
};

// A concrete test case.
struct MyTest: public Combine<Login, Device>
{
    void test() { std::cout << "test" << std::endl; }
};

int main()
{
    MyTest cd;
    cd.setUp();
    cd.test();
    cd.tearDown();
    Combine<Device> d;
    d.setUp();
    d.tearDown();
    return 0;
}

输出:

Login setup
Device setup
test
Login teardown
Device teardown
Device setup
Device teardown

Answer 1

使用 mixins、多重继承和 super() 调用:

import unittest

class MixinBase(object):
    def setUp(self):
        pass

    def tearDown(self):
        pass


class LoginMixin(MixinBase):
    def setUp(self):
        print("LoginMixin.setUp()")
        self.login = "login"
        super(LoginMixin, self).setUp()

    def tearDown(self):
        super(LoginMixin, self).tearDown()
        print("LoginMixin.tearDown()")
        del self.login


class DeviceMixin(MixinBase):
    def setUp(self):
        print("DeviceMixin.setUp()")
        self.device = "device"
        super(DeviceMixin, self).setUp()

    def tearDown(self):
        super(DeviceMixin, self).tearDown()
        print("DeviceMixin.tearDown()")
        del self.device



class TestThatOnlyNeedsLogin(LoginMixin, unittest.TestCase):
    def test_something(self):
        self.assertEqual(self.login, "login")


class TestThatNeedsLoginAndDevice(LoginMixin, DeviceMixin, unittest.TestCase):
    def test_something(self):
        self.assertEqual(self.login, "login")
        self.assertEqual(self.device, "device")

# XXX actually useless (multiple inheritance works fine)
# but since you asked for it
def combinemixins(cls, *otherbases):
    bases = (cls,)  + otherbases
    Combined = type.__new__(type, "Combined", bases, {})
    return Combined

LoginAndDevice = combinemixins(LoginMixin, DeviceMixin)

class TestWithCombined(LoginAndDevice, unittest.TestCase):
    def test_something(self):
        self.assertEqual(self.login, "login")
        self.assertEqual(self.device, "device")


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