9、参数化

问题背景

当我们写好一个函数进行自测的时候，通常需要多种数据场景进行验证，例如我写了一个乘法计算器函数：

import pytest
def func(a: int, b: int):
    return a*b
def test01():
    assert func(1, 2) == 2
    assert func(2, 2) == 4
    assert func(3, 2) == 6
    assert func(4, 2) == 9
if __name__ == '__main__':
    pytest.main(['参数化.py', '-s'])

执行结果：

collected 1 item
参数化.py F
================================== FAILURES ===================================
___________________________________ test01 ____________________________________
def test01():
assert func(1, 2) == 2
assert func(2, 2) == 4
assert func(3, 2) == 6
>       assert func(4, 2) == 9
E       assert 8 == 9
E        +  where 8 = func(4, 2)
参数化.py:22: AssertionError
=========================== short test summary info ===========================
FAILED 参数化.py::test01 - assert 8 == 9
============================== 1 failed in 0.22s ==============================
***Repl Closed***

通过在测试用例中输入不同的测试数据，进行场景编写，可实现所需要的目的。但是，这样的，测试用例维护性不强，耦合度高，可拓展性低，如果某天对func()函数进行重构，则涉及到的用例全部需要维护。

@pytest.mark.parametrize进行参数化

pytest提供@pytest.mark.parametriza 可以实现参数化：

import pytest
def func(a: int, b: int):
    return a*b
@pytest.mark.parametrize("intA,intB,expected",[(1,2,2),(2,2,4),(3,3,9),(4,4,15)])
def test01(intA,intB,expected):
    print(f"{intA}*{intB}={expected}")
    assert func(intA,intB) == expected
if __name__ == '__main__':
    pytest.main(['参数化.py', '-s'])

执行结果：

collected 4 items
参数化.py 
 1*2=2
.2*2=4
.3*3=9
.4*4=15
F
================================== FAILURES ===================================
_______________________________ test01[4-4-15] ________________________________
intA = 4, intB = 4, expected = 15
    @pytest.mark.parametrize("intA,intB,expected",[(1,2,2),(2,2,4),(3,3,9),(4,4,15)])
    def test01(intA,intB,expected):
        print(f"{intA}*{intB}={expected}")
>       assert func(intA,intB) == expected
E       assert 16 == 15
E        +  where 16 = func(4, 4)
参数化.py:20: AssertionError
=========================== short test summary info ===========================
FAILED 参数化.py::test01[4-4-15] - assert 16 == 15
========================= 1 failed, 3 passed in 0.22s =========================
***Repl Closed***

使用实例

import pytest
def loginDemo(loginName: str, password: str):
    if loginName == "admin" and password == "123456":
        return {"success": True, "loginInfo": "admin用户登录成功"}
    elif loginName == "tester" and password == "123123":
        return {"success": True, "loginInfo": "tester用户登录成功"}
    else:
        return {"success": False, "loginInfo": "该用户不允许登录或密码错误"}
data = [{"loginName": "admin", "password": "123456"}, {"loginName": "tester", "password": "123123"}, {"loginName": "hello", "password": "123456"}]
@pytest.mark.parametrize('dic', data)
def test01(dic):
    assert loginDemo(dic['loginName'],dic['password'])['success'] == True
if __name__ == '__main__':
    pytest.main(['参数化.py', '-s'])

执行结果：

collected 3 items
参数化.py ..F
================================== FAILURES ===================================
________________________________ test01[dic2] _________________________________
dic = {'loginName': 'hello', 'password': '123456'}
    @pytest.mark.parametrize('dic', data)
    def test01(dic):
>       assert loginDemo(dic['loginName'],dic['password'])['success'] == True
E       assert False == True
参数化.py:20: AssertionError
=========================== short test summary info ===========================
FAILED 参数化.py::test01[dic2] - assert False == True
========================= 1 failed, 2 passed in 0.21s =========================
***Repl Closed***