python - 测试具有用户输入的 python 函数的问题 (pytest)

Question

我的测试有一些问题。我想用一些简单的脚本(在这种情况下是 BMI 计数器)开始我的 pytest 冒险。我想测试一次功能，但测试将进入所有功能。如果我对输入值进行了注释，则测试通过。

输出:

$ pytest test_bmi.py
=========================================================================================== test session starts ============================================================================================
platform darwin -- Python 3.7.1, pytest-4.0.2, py-1.7.0, pluggy-0.8.0
rootdir: /Users/mateusz/Documents/Code_Me_Python/zajecia_python/Zajecia_1, inifile:
plugins: remotedata-0.3.1, openfiles-0.3.1, doctestplus-0.2.0, arraydiff-0.3
collected 0 items / 1 errors

================================================================================================== ERRORS ==================================================================================================
_______________________________________________________________________________________ ERROR collecting test_bmi.py _______________________________________________________________________________________
test_bmi.py:1: in <module>
    from bmi import count_bmi
bmi.py:14: in <module>
    main()
bmi.py:11: in main
    (mass, height) = users_data()
bmi.py:2: in users_data
    mass = float(input("Your weight: "))
../../../../anaconda3/lib/python3.7/site-packages/_pytest/capture.py:656: in read
    raise IOError("reading from stdin while output is captured")
E   OSError: reading from stdin while output is captured
--------------------------------------------------------------------------------------------- Captured stdout ----------------------------------------------------------------------------------------------
Your weight:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 1 errors during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
========================================================================================= 1 error in 0.16 seconds =========================================================================================

我已经尝试过“monkeypatch”(如代码片段中所述)，将值输入变量以将它们传递给测试。没有任何帮助。

体重指数

def users_data():
    mass = float(input("Your weight: "))
    height = float(input("Your height: "))
    return mass, height

def count_bmi(mass, height):
    bmi = round(mass / (height**2), 2)
    return bmi

def main():
    (mass, height) = users_data()
    print(count_bmi(mass, height))

main()

test_bmi.py

from bmi import count_bmi

def test_count_bmi(monkeypatch):
    ans1 = '60'
    ans2 = '1.7'
    ans3 = '20.76'
    with monkeypatch.context() as m:
        m.setattr('builtins.input', lambda x: ans1, ans2)
        result = count_bmi(ans1, ans2)

    assert result == ans3

如果我注释输入变量

 def test_count_bmi(self):
     count_bmi.input = lambda: ''
     output = count_bmi(60, 1.7)  
     assert output == '20.76'

我希望通过考试。

Answer 1

问题是模块级别的调用main()。这将在 bmi 模块导入时执行 main 函数；使用常见的习语来规避这一点:

# bmi.py

def users_data():
    ...

def count_bmi(mass, height):
    ...

def main():
    ...

if __name__ == "__main__":
    # execute only if run as a script
    main()

见题目__main__ — Top-level script environment在 Python 文档中，如果你想了解更多；另外，SO 对此有一个很好的问题:What does if __name__ == “__main__”: do?