CS50P: 5. Unit Tests

assert

python: assert

calculator.py :

def main():
    x = int(input("What's x? "))
    print("x squared is", square(x))
def square(n):
    return n + n    #刻意为之
if __name__ == "__main__":
    main()

test_calculator.py :

from calculator import square
def main():
    test_square()
def test_square():
    assert square(2) == 4
    assert square(3) == 9
if __name__ == "__main__":
    main()

在终端运行，得到 AssertionError ，同样可以用 try & except 语句

def test_square():
    try:
        assert square(2) == 4
    except AssertionError:
        print("2 squared is not 4")
    try:
        assert square(3) == 9
    except AssertionError:
        print("3 squared is not 9")
    try:
        assert square(-2) == 4
    except AssertionError:
        print("-2 squared is not 4")
    try:
        assert square(-3) == 9
    except AssertionError:
        print("-3 squared is not 9")
    try:
        assert square(0) == 0
    except AssertionError:
        print("0 squared is not 0")

pytest

pytest’s documentation

可以测试函数的第三方库，相当于帮我们做了 try & except

示例

test_calculator.py :

from calculator import square
def test_square():
    assert square(2) == 4
    assert square(3) == 9
    assert square(-2) == 4
    assert square(-3) == 9
    assert square(0) == 0

注意到没有 main 函数了

运行 pytest test_calculator.py

categories test

上例中遇到错误即停止，但我们往往希望一次获得更多的错误信息，以便debug，需要分割测试数据

代码：

def test_positive():
    assert square(2) == 4
    assert square(3) == 9

def test_negative():
    assert square(-2) == 4
    assert square(-3) == 9

def test_zero():
    assert square(0) == 0

运行结果：（F == Fail；. == Pass）

某一函数测试出错，之后的函数照旧进行测试。

特例——用户输入字符串

应用 pytest 库中的 raises 函数

import pytest

def test_str():
    with pytest.raises(TypeError):
        square("cat")

括号内是可能发生的错误类型，什么时候期望错误被提出？当输入字符时会

tests文件夹

当需要对多个函数进行测试时，往往将测试文件整理为一个文件夹

Command window :

mkdir test
code test/__init__.py

空的 __init__.py 指示出 test 文件夹不单单是file或module，是一个package，里面有可以进行测试的文件

测试时：

pytest test