python怎么测试程序_Python 程序的测试
测试的种类
根据关注点不同，测试分为两大类acceptance tests： 也就说，测试需要完成的功能，是否都已经实现
unit test：测试程序中不同的模块，是否能够正常、正确的相互调用
这两大类里面，都包含以下三个方面：exploratory testing
regression testing
integration testing
测试程序
doctest
这是一个自动化的测试程序，你把你的测试命令写在 docstring 或者 readme.txt，这个 package 会帮你做测试。
举个栗子
"""
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()
运行代码
python example.py -v
得到的结果如下
Trying:
factorial(5)
Expecting:
120
ok
Trying:
[factorial(n) for n in range(6)]
Expecting:
[1, 1, 2, 6, 24, 120]
ok
Trying:
factorial(1e100)
Expecting:
Traceback (most recent call last):
...
OverflowError: n too large
ok
2 items passed all tests:
1 tests in __main__
8 tests in __main__.factorial
9 tests in 2 items.
9 passed and 0 failed.
Test passed.
这种测试方法不适合大规模测试。
手工写测试
主要用到的语法是
try ... except ... 和 assert
比如
import sys
def test_quadroots_types():
try:
quad_roots("", "green", "hi")
except:
assert(sys.exc_info()[0] == TypeError)
test_quadroots_types()
import sys
def test_quadroots_zerocoeff():
try:
quad_roots(a=0.0)
except:
assert(sys.exc_info()[0] == ValueError)
test_quadroots_zerocoeff()
pytest
这里用实例来说明这个包怎么用。
首先，我们有一个 root 函数
%%file roots.py
def quad_roots(a=1.0, b=2.0, c=0.0):
"""Returns the roots of a quadratic equation: ax^2 + bx + c = 0.
INPUTS
=======
a: float, optional, default value is 1
Coefficient of quadratic term
b: float, optional, default value is 2
Coefficient of linear term
c: float, optional, default value is 0
Constant term
RETURNS
========
roots: 2-tuple of complex floats
Has the form (root1, root2) unless a = 0
in which case a ValueError exception is raised
EXAMPLES
=========
>>> quad_roots(1.0, 1.0, -12.0)
((3+0j), (-4+0j))
"""
import cmath # Can return complex numbers from square roots
if a == 0:
raise ValueError("The quadratic coefficient is zero. This is not a quadratic equation.")
else:
sqrtdisc = cmath.sqrt(b * b - 4.0 * a * c)
r1 = -b + sqrtdisc
r2 = -b - sqrtdisc
twoa = 2.0 * a
return (r1 / twoa, r2 / twoa)
然后写一个 test 文件
%%file test_roots.py
import pytest
import roots
def test_quadroots_result():
assert roots.quad_roots(1.0, 1.0, -12.0) == ((3+0j), (-4+0j))
def test_quadroots_types():
with pytest.raises(TypeError):
roots.quad_roots("", "green", "hi")
def test_quadroots_zerocoeff():
with pytest.raises(ValueError):
roots.quad_roots(a=0.0)
最后调用 pytest
python -m pytest ./test_roots.py
输出结果大概长这样
============================= test session starts ==============================
platform darwin -- Python 3.6.7, pytest-3.8.2, py-1.6.0, pluggy-0.7.1
rootdir: xx
plugins: remotedata-0.3.0, openfiles-0.3.0, doctestplus-0.1.3, cov-2.5.1, arraydiff-0.2
collected 3 items
test_roots.py ... [100%]
=========================== 3 passed in 0.03 seconds ===========================
pytest-cov
有时候，一个文件里面的函数很多，你希望确保所有的函数都被测试程序覆盖掉了。所以这个时候需要 pytest-cov 上场了。
%%file roots.py
def linear_roots(a=1.0, b=0.0):
"""Returns the roots of a linear equation: ax+ b = 0.
INPUTS
=======
a: float, optional, default value is 1
Coefficient of linear term
b: float, optional, default value is 0
Coefficient of constant term
RETURNS
========
roots: 1-tuple of real floats
Has the form (root) unless a = 0
in which case a ValueError exception is raised
EXAMPLES
=========
>>> linear_roots(1.0, 2.0)
-2.0
"""
if a == 0:
raise ValueError("The linear coefficient is zero. This is not a linear equation.")
else:
return ((-b / a))
def quad_roots(a=1.0, b=2.0, c=0.0):
"""Returns the roots of a quadratic equation: ax^2 + bx + c = 0.
INPUTS
=======
a: float, optional, default value is 1
Coefficient of quadratic term
b: float, optional, default value is 2
Coefficient of linear term
c: float, optional, default value is 0
Constant term
RETURNS
========
roots: 2-tuple of complex floats
Has the form (root1, root2) unless a = 0
in which case a ValueError exception is raised
EXAMPLES
=========
>>> quad_roots(1.0, 1.0, -12.0)
((3+0j), (-4+0j))
"""
import cmath # Can return complex numbers from square roots
if a == 0:
raise ValueError("The quadratic coefficient is zero. This is not a quadratic equation.")
else:
sqrtdisc = cmath.sqrt(b * b - 4.0 * a * c)
r1 = -b + sqrtdisc
r2 = -b - sqrtdisc
twoa = 2.0 * a
return (r1 / twoa, r2 / twoa)
然后加入还是只测试 quad_roots 这个函数，故意漏掉 linear_roots。看看 pytest-cov 能不能帮我们发现。
运行 python -m pytest ./test_roots.py --cov --cov-report term-missing
============================= test session starts ==============================
platform darwin -- Python 3.6.7, pytest-3.8.2, py-1.6.0, pluggy-0.7.1
rootdir: xx
plugins: remotedata-0.3.0, openfiles-0.3.0, doctestplus-0.1.3, cov-2.5.1, arraydiff-0.2
collected 3 items
test_roots.py ... [100%]
---------- coverage: platform darwin, python 3.6.7-final-0 -----------
Name Stmts Miss Cover Missing
---------------------------------------------
roots.py 13 3 77% 22-25
test_roots.py 10 0 100%
---------------------------------------------
TOTAL 23 3 87%
=========================== 3 passed in 0.04 seconds ===========================
可以告诉你 line 22-25 没有 cover 到。