使用 doctest 模块在Python中进行测试

Python中的文档Python不仅用于描述类或函数，以更好地理解代码和使用，还用于测试目的。

Doctest 模块在文档字符串中查找类似于交互式 shell 命令的模式。

输入和预期输出包含在文档字符串中，然后 doctest 模块使用此文档字符串来测试处理后的输出。
解析完文档字符串后，解析后的文本将作为Python shell 命令执行，并将结果与从文档字符串中获取的预期结果进行比较。

这是一个简单的例子：

1. import testmod from doctest to test the function.
2. Define our test function.
3. Provide a suitable docstring containing desired output on certain inputs.
4. Define the logic.
5. Call the testmod function with the name of the function to test and set verbose True as arguments.

Note: All the arguments are optional. The name of the function is explicitly passed to the testmod. It’s useful if there are multiple functions.

执行

# import testmod for testing our function
from doctest import testmod
  
# define a function to test
def factorial(n):
    '''
    This function calculates recursively and
    returns the factorial of a positive number.
    Define input and expected output:
    >>> factorial(3)
    6
    >>> factorial(5)
    120
    '''
    if n <= 1:
        return 1
    return n * factorial(n - 1)
  
# call the testmod function
if __name__ == '__main__':
    testmod(name ='factorial', verbose = True)

输出：

Trying:
    factorial(3)
Expecting:
    6
ok
Trying:
    factorial(5)
Expecting:
    120
ok
1 items had no tests:
    factorial
1 items passed all tests:
   2 tests in factorial.factorial
2 tests in 2 items.
2 passed and 0 failed.
Test passed.

现在，测试失败。如果我们的逻辑错了怎么办？

# import testmod for testing our function
from doctest import testmod
  
# define a function to test
def factorial(n):
    '''
    This function calculates recursively and
    returns the factorial of a positive number.
    Define input and expected output:
    >>> factorial(3)
    6
    >>> factorial(5)
    120
    '''
    if n <= 1:
        return 1
    # wrong logic for factorial
    return factorial(n - 1)
  
# call the testmod function
if __name__ == '__main__':
    testmod(name ='factorial', verbose = True)

输出：

Trying:
    factorial(3)
Expecting:
    6
**********************************************************************
File "woking_with_csv.py", line 33, in factorial.factorial
Failed example:
    factorial(3)
Expected:
    6
Got:
    1
Trying:
    factorial(5)
Expecting:
    120
**********************************************************************
File "woking_with_csv.py", line 35, in factorial.factorial
Failed example:
    factorial(5)
Expected:
    120
Got:
    1
1 items had no tests:
    factorial
**********************************************************************
1 items had failures:
   2 of   2 in factorial.factorial
2 tests in 2 items.
0 passed and 2 failed.
***Test Failed*** 2 failures.

注意：如果 'verbose' 设置为 False（默认），输出将仅在失败的情况下显示，而不是在成功的情况下显示。