Python自动化——pytest常用插件详解

前言

Pytest是Python的一种单元测试框架，与unittest相比，使用起来更简洁、效率更高，也是目前大部分使用python编写测试用例的小伙伴们的第一选择了。

除了框架本身提供的功能外，Pytest还支持上百种第三方插件，良好的扩展性可以更好的满足大家在用例设计时的不同需求。本文将为大家详细介绍下面6项常用的插件。废话就不多说了我们直接开始吧。

1、失败重跑 pytest-rerunfailures

　　安装：pip install pytest-rerunfailures

　　使用：pytest test_class.py --reruns 5 --reruns-delay 1 -vs （失败后重新运行5次，每次间隔1秒）

　　　　　@pytest.mark.flaky(reruns = 5 ,reruns-delay = 1 )　指定某个用例

#!/usr/bin/python
# -*- coding: UTF-8 -*-
"""
@author:chenshifeng
@file:test_calc2.py
@time:2020/09/16
"""

import pytest


@pytest.mark.parametrize('a,b,result', [
    (1, 1, 3),
    (2, 2, 4),
    (100, 100, 200),
    (0.1, 0.1, 0.2),
    (-1, -1, -2)
], ids=['int', 'int', 'bignum', 'float', 'fushu'])  # 参数化
def test_add(a, b, result):
    # cal = Calculator()
    assert result == a + b

命令行执行：

pytest test_calc2.py --reruns 5 --reruns-delay 1 -vs

结果如下：

============================================================================= test session starts =============================================================================
platform darwin -- Python 3.6.4, pytest-6.0.2, py-1.9.0, pluggy-0.13.1 -- /Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6
cachedir: .pytest_cache
rootdir: /Users/chenshifeng/MyCode/PythonCode/SFDSZL/test_pytest, configfile: pytest.ini
plugins: rerunfailures-9.1, dependency-0.5.1, ordering-0.6, assume-2.3.2
collected 5 items                                                                                                                                                             

test_calc2.py::test_add[int0] RERUN
test_calc2.py::test_add[int0] RERUN
test_calc2.py::test_add[int0] RERUN
test_calc2.py::test_add[int0] RERUN
test_calc2.py::test_add[int0] RERUN
test_calc2.py::test_add[int0] FAILED
test_calc2.py::test_add[int1] PASSED
test_calc2.py::test_add[bignum] PASSED
test_calc2.py::test_add[float] PASSED
test_calc2.py::test_add[fushu] PASSED

================================================================================== FAILURES ===================================================================================
_______________________________________________________________________________ test_add[int0] ________________________________________________________________________________

a = 1, b = 1, result = 3

    @pytest.mark.parametrize('a,b,result', [
        (1, 1, 3),
        (2, 2, 4),
        (100, 100, 200),
        (0.1, 0.1, 0.2),
        (-1, -1, -2)
    ], ids=['int', 'int', 'bignum', 'float', 'fushu'])  # 参数化
    def test_add(a, b, result):
        cal = Calculator()
>       assert result == cal.add(a, b)
E       assert 3 == 2
E         +3
E         -2

test_calc2.py:26: AssertionError
=========================================================================== short test summary info ===========================================================================
FAILED test_calc2.py::test_add[int0] - assert 3 == 2
==================================================================== 1 failed, 4 passed, 5 rerun in 5.11s =====================================================================

通过装饰器设置重跑次数与延时时间

#!/usr/bin/python
# -*- coding: UTF-8 -*-
"""
@author:chenshifeng
@file:test_calc2.py
@time:2020/09/16
"""

import pytest


@pytest.mark.parametrize('a,b,result', [
    (1, 1, 3),
    (2, 2, 4),
    (100, 100, 200),
    (0.1, 0.1, 0.2),
    (-1, -1, -2)
], ids=['int', 'int', 'bignum', 'float', 'fushu'])  # 参数化
# 通过装饰器设置重跑次数
@pytest.mark.flaky(reruns=6, reruns_delay=2)
def test_add(a, b, result):
    # cal = Calculator()
    assert result == a + b

结果：

Testing started at 10:10 下午 ...
/usr/local/bin/python3.6 "/Applications/PyCharm CE.app/Contents/plugins/python-ce/helpers/pycharm/_jb_pytest_runner.py" --target test_calc2.py::test_add
Launching pytest with arguments test_calc2.py::test_add in /Users/chenshifeng/MyCode/PythonCode/SFDSZL/test_pytest/testcode

============================= test session starts ==============================
platform darwin -- Python 3.6.4, pytest-6.0.2, py-1.9.0, pluggy-0.13.1 -- /usr/local/bin/python3.6
cachedir: .pytest_cache
rootdir: /Users/chenshifeng/MyCode/PythonCode/SFDSZL/test_pytest, configfile: pytest.ini
plugins: rerunfailures-9.1, dependency-0.5.1, ordering-0.6, assume-2.3.2
collecting ... collected 5 items

test_calc2.py::test_add[int0] RERUN                                      [ 20%]
test_calc2.py::test_add[int0] RERUN                                      [ 20%]
test_calc2.py::test_add[int0] RERUN                                      [ 20%]
test_calc2.py::test_add[int0] RERUN                                      [ 20%]
test_calc2.py::test_add[int0] RERUN                                      [ 20%]
test_calc2.py::test_add[int0] RERUN                                      [ 20%]
test_calc2.py::test_add[int0] FAILED                                     [ 20%]
testcode/test_calc2.py:11 (test_add[int0])
3 != 2

Expected :2
Actual   :3
<Click to see difference>

a = 1, b = 1, result = 3

    @pytest.mark.parametrize('a,b,result', [
        (1, 1, 3),
        (2, 2, 4),
        (100, 100, 200),
        (0.1, 0.1, 0.2),
        (-1, -1, -2)
    ], ids=['int', 'int', 'bignum', 'float', 'fushu'])  # 参数化
    # 通过装饰器设置重跑次数
    @pytest.mark.flaky(reruns=6, reruns_delay=2)
    def test_add(a, b, result):
        # cal = Calculator()
>       assert result == a + b
E       assert 3 == 2

test_calc2.py:23: AssertionError
PASSED                                     [ 40%]PASSED                                   [ 60%]PASSED                                    [ 80%]PASSED                                    [100%]
Assertion failed

Assertion failed

Assertion failed

Assertion failed

test_calc2.py::test_add[int1] 
test_calc2.py::test_add[bignum] 
test_calc2.py::test_add[float] 
test_calc2.py::test_add[fushu] 

=================================== FAILURES ===================================
________________________________ test_add[int0] ________________________________

a = 1, b = 1, result = 3

    @pytest.mark.parametrize('a,b,result', [
        (1, 1, 3),
        (2, 2, 4),
        (100, 100, 200),
        (0.1, 0.1, 0.2),
        (-1, -1, -2)
    ], ids=['int', 'int', 'bignum', 'float', 'fushu'])  # 参数化
    # 通过装饰器设置重跑次数
    @pytest.mark.flaky(reruns=6, reruns_delay=2)
    def test_add(a, b, result):
        # cal = Calculator()
>       assert result == a + b
E       assert 3 == 2

test_calc2.py:23: AssertionError
=========================== short test summary info ============================
FAILED test_calc2.py::test_add[int0] - assert 3 == 2
==================== 1 failed, 4 passed, 6 rerun in 12.13s =====================

Process finished with exit code 1

Assertion failed

Assertion failed

Assertion failed

Assertion failed

2、多重校验 pytest-assume

　　正常情况下一条用例如果有多条断言，一条断言失败了，其他断言就不会执行了，而使用pytest-assume可以继续执行下面的断言

　　　　安装 ： pip install pytest-assume

　　　　执行 ： pytest.assume(1==3)

for example：

#!/usr/bin/python
# -*- coding: UTF-8 -*-
"""
@author:chenshifeng
@file:test_calc2.py
@time:2020/09/16
"""

import pytest


def test_assume():
    print('登录操作')
    pytest.assume(1 == 2)
    print('搜索操作')
    pytest.assume(2 == 2)
    print('加购操作')
    pytest.assume(3 == 2)

运行结果：

Testing started at 10:23 下午 ...
/usr/local/bin/python3.6 "/Applications/PyCharm CE.app/Contents/plugins/python-ce/helpers/pycharm/_jb_pytest_runner.py" --target test_calc2.py::test_assume
Launching pytest with arguments test_calc2.py::test_assume in /Users/chenshifeng/MyCode/PythonCode/SFDSZL/test_pytest/testcode

============================= test session starts ==============================
platform darwin -- Python 3.6.4, pytest-6.0.2, py-1.9.0, pluggy-0.13.1 -- /usr/local/bin/python3.6
cachedir: .pytest_cache
rootdir: /Users/chenshifeng/MyCode/PythonCode/SFDSZL/test_pytest, configfile: pytest.ini
plugins: rerunfailures-9.1, dependency-0.5.1, ordering-0.6, assume-2.3.2
collecting ... collected 1 item

test_calc2.py::test_assume FAILED                                        [100%]登录操作
搜索操作
加购操作

testcode/test_calc2.py:11 (test_assume)
tp = <class 'pytest_assume.plugin.FailedAssumption'>, value = None, tb = None

    def reraise(tp, value, tb=None):
        try:
            if value is None:
                value = tp()
            if value.__traceback__ is not tb:
>               raise value.with_traceback(tb)
E               pytest_assume.plugin.FailedAssumption: 
E               2 Failed Assumptions:
E               
E               test_calc2.py:14: AssumptionFailure
E               >>    pytest.assume(1 == 2)
E               AssertionError: assert False
E               
E               test_calc2.py:18: AssumptionFailure
E               >>    pytest.assume(3 == 2)
E               AssertionError: assert False

/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/six.py:702: FailedAssumption

Assertion failed

Assertion failed


=================================== FAILURES ===================================
_________________________________ test_assume __________________________________

tp = <class 'pytest_assume.plugin.FailedAssumption'>, value = None, tb = None

    def reraise(tp, value, tb=None):
        try:
            if value is None:
                value = tp()
            if value.__traceback__ is not tb:
>               raise value.with_traceback(tb)
E               pytest_assume.plugin.FailedAssumption: 
E               2 Failed Assumptions:
E               
E               test_calc2.py:14: AssumptionFailure
E               >>    pytest.assume(1 == 2)
E               AssertionError: assert False
E               
E               test_calc2.py:18: AssumptionFailure
E               >>    pytest.assume(3 == 2)
E               AssertionError: assert False

/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/six.py:702: FailedAssumption
----------------------------- Captured stdout call -----------------------------
登录操作
搜索操作
加购操作
=========================== short test summary info ============================
FAILED test_calc2.py::test_assume - pytest_assume.plugin.FailedAssumption: 
============================== 1 failed in 0.09s ===============================

Process finished with exit code 1

Assertion failed

Assertion failed

Assertion failed

Assertion failed

3、设定执行顺序 pytest-ordering

　　正常情况下，用例默认执行顺序是自上而下的，对于一些有上下文依赖关系的用例，可是通过 pytest-ordering 来设置执行顺序，当然，通过setup、teardown和fixture来解决也是可以的

　　安装插件 ： pip install pytest-ordering

　　使用方法 ： @pytest.mark.run(order=2)

　　需要注意的是，当有多个装饰器的时候，可能会发生冲突（比如参数化）

For example, this:

import pytest

@pytest.mark.run(order=2)
def test_foo():
    assert True

@pytest.mark.run(order=1)
def test_bar():
    assert True

Yields this output:

============================= test session starts ==============================
platform darwin -- Python 3.6.4, pytest-6.0.2, py-1.9.0, pluggy-0.13.1 -- /usr/local/bin/python3.6
cachedir: .pytest_cache
rootdir: /Users/chenshifeng/MyCode/PythonCode/SFDSZL/test_pytest, configfile: pytest.ini
plugins: rerunfailures-9.1, dependency-0.5.1, ordering-0.6, assume-2.3.2
collecting ... collected 2 items

test_ordering.py::test_bar 
test_ordering.py::test_foo 

============================== 2 passed in 0.02s ===============================

4、用例依赖（pytest-dependency）

使用该插件可以标记一个testcase作为其他testcase的依赖，当依赖项执行失败时，那些依赖它的test将会被跳过。

安装 ： pip install pytest-dependency

使用方法： 用 @pytest.mark.dependency()对所依赖的方法进行标记，使用@pytest.mark.dependency(depends=["test_name"])引用依赖,test_name可以是多个。

上用例：

import pytest

@pytest.mark.dependency()
def test_01():
    assert False

@pytest.mark.dependency(depends=["test_01"])
def test_02():
    print("执行测试2")

output：

=========================== short test summary info ============================
FAILED test_ordering.py::test_01 - assert False
========================= 1 failed, 1 skipped in 0.06s =========================

Process finished with exit code 1

5.分布式测试(pytest-xdist)

• 平常我们功能测试用例非常多时，比如有1千条用例，假设每个用例执行需要1分钟，如果单个测试人员执行需要1000分钟才能跑完
• 当项目非常紧急时，会需要协调多个测试资源来把任务分成两部分，于是执行时间缩短一半，如果有10个小伙伴，那么执行时间就会变成十分之一，大大节省了测试时间
• 为了节省项目测试时间，10个测试同时并行测试，这就是一种分布式场景

　分布式执行用例的原则：

• 用例之间是独立的，没有依赖关系，完全可以独立运行用例执行没有顺序要求，随机顺序都能正常执行每个用例都能重复运行，运行结果不会影响其他用例

　　插件安装：
　　　　　　pip3 install pytest-xdist -i http://pypi.douban.com/simple/ --trusted-host http://pypi.douban.com

　　使用方法：

　　　　　　pytest -n 2 (2代表2个CPU)

　　　　　　pytest -n auto

• nauto：可以自动检测到系统的CPU核数；从测试结果来看，检测到的是逻辑处理器的数量，即假12核使用auto等于利用了所有CPU来跑用例，此时CPU占用率会特别高

6.生成报告（pytest-html）

pytest-html是一个插件，pytest用于生成测试结果的HTML报告。兼容Python 2.7,3.6

安装插件： pip install pytest-html

使用方法： pytest --html=report.html

7、总结

本文为大家介绍了一些常用的pytest框架的插件，可以帮助我们解决一些实际使用过程中遇到的问题。目前，pytest支持的插件有很多个，除了本文介绍的6个常用插件外，还有很多支持其它需求的插件，大家可以根据自己的需要尝试查找使用相关的插件，以便能够更好的设计出符合业务场景的测试用例。

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