python doctest測試

---

title: Python doctest測試
tags: Python
---

doctest測試

python 提供了REPL（read-eval-print loop，讀取、求值、輸出的循環）

官方地址：https://docs.python.org/3/library/doctest.html

"""
This is the "example" module.

The example module supplies one function, factorial().  For example,

>>> factorial(5)
120
"""

def factorial(n):
    """Return the factorial of n, an exact integer >= 0.

    >>> [factorial(n) for n in range(6)]
    [1, 1, 2, 6, 24, 120]
    >>> factorial(30)
    265252859812191058636308480000000
    >>> factorial(-1)
    Traceback (most recent call last):
        ...
    ValueError: n must be >= 0

    Factorials of floats are OK, but the float must be an exact integer:
    >>> factorial(30.1)
    Traceback (most recent call last):
        ...
    ValueError: n must be exact integer
    >>> factorial(30.0)
    265252859812191058636308480000000

    It must also not be ridiculously large:
    >>> factorial(1e100)
    Traceback (most recent call last):
        ...
    OverflowError: n too large
    """

    import math
    if not n >= 0:
        raise ValueError("n must be >= 0")
    if math.floor(n) != n:
        raise ValueError("n must be exact integer")
    if n+1 == n:  # catch a value like 1e300
        raise OverflowError("n too large")
    result = 1
    factor = 2
    while factor <= n:
        result *= factor
        factor += 1
    return result


if __name__ == "__main__":
    import doctest
    doctest.testmod()

執行Python3 test.py -v

結果：

Trying:
    factorial(5)
Expecting:
    120
ok
Trying:
    [factorial(n) for n in range(6)]
Expecting:
    [1, 1, 2, 6, 24, 120]
ok
Trying:
    factorial(30)
Expecting:
    265252859812191058636308480000000
**********************************************************************
File "test.py", line 15, in __main__.factorial
Failed example:
    factorial(30)
Expected:
    265252859812191058636308480000000
Got:
    265252859812191058636308480000000L
Trying:
    factorial(-1)
Expecting:
    Traceback (most recent call last):
        ...
    ValueError: n must be >= 0
ok
Trying:
    factorial(30.1)
Expecting:
    Traceback (most recent call last):
        ...
    ValueError: n must be exact integer
ok
Trying:
    factorial(30.0)
Expecting:
    265252859812191058636308480000000
**********************************************************************
File "test.py", line 27, in __main__.factorial
Failed example:
    factorial(30.0)
Expected:
    265252859812191058636308480000000
Got:
    265252859812191058636308480000000L
Trying:
    factorial(1e100)
Expecting:
    Traceback (most recent call last):
        ...
    OverflowError: n too large
ok
1 items passed all tests:
   1 tests in __main__
**********************************************************************
1 items had failures:
   2 of   6 in __main__.factorial
7 tests in 2 items.
5 passed and 2 failed.
***Test Failed*** 2 failures.