使用 doctest 测试 Python 代码时出现意外错误

Question

我正在使用 doctest 测试我的代码，但在测试一个生成两行文本输出的简单函数时出现意外错误。为什么？

Python 3.6.9 在 Ubuntu 18.04。 Python 2.7 和 Python 3.9.

可以观察到相同的错误

测试程序（另存为doctest-bugs.py）：

#!/usr/bin/env python3

def testme():
    """
    Emit test message.

    >>> testme()
    First line (no leading spaces)
     Second line (one leading space)
    """
    return """First line (no leading spaces)
 Second line (one leading space)"""

常规运行:

$ python3 doctest-bugs.py

测试 doctest:

$ python3 -m doctest doctest-bugs.py 
**********************************************************************
File "/home/filip/doctest-bugs.py", line 7, in doctest-bugs.testme
Failed example:
    testme()
Expected:
    First line (no leading spaces)
     Second line (one leading space)
Got:
    'First line (no leading spaces)\n Second line (one leading space)'
**********************************************************************
1 items had failures:
   1 of   1 in doctest-bugs.testme
***Test Failed*** 1 failures.

所有字符串都是逐字记录的，根据模块文档，应该可以毫无问题地识别单个前导space。

Answer 1

该函数不产生两行输出；它 returns 一个包含两行的字符串。

>>> testme()
'First line (no leading spaces)\n Second line (one leading space)'

也许您混淆了返回和打印。

>>> print(testme())
First line (no leading spaces)
 Second line (one leading space)

这是一个工作示例：

def testme():
    """
    >>> testme()
    'First line (no leading spaces)\n Second line (one leading space)'
    >>> print(testme())
    First line (no leading spaces)
     Second line (one leading space)
    """
    return """First line (no leading spaces)
 Second line (one leading space)"""

使用 doctest 测试 Python 代码时出现意外错误

Unexpected errors while testing Python code with doctest

python

doctest

python-3.x