Selenium3自动化测试38单元测试Pytest

业无高卑志当坚，男儿有求安得闲？这篇文章主要讲述Selenium3自动化测试38单元测试Pytest相关的知识，希望能为你提供帮助。
1.Pytest介绍pytest测试框架也是主流的一个测试框架，推荐使用该框架，对比unnitest框架来说，其不需要像unittest那样单独创建类继承unittest.TestCase。它使用起来非常简单，只需要创建测试类或者测试文件，然后以test开头即可，pytest可以按照这个规则找到测试用例并执行。
pytest测试框架，主要有以下几个特点：

简单灵活，容易上手，文档丰富；
支持用简单的assert语句实现丰富的断言，无需复杂的self.assert*函数
支持参数化；
兼容unittest和 nose测试集
能够支持简单的单元测试和复杂的功能测试，还可应用到接口自动化测试（pytest+requests）中；
丰富的插件生态，具有很多第三方插件，并且可以自定义扩展，如pytest-Selenium（集成Selenium）等；
支持重复执行失败的case等；
方便和持续集成工具jenkins集成；
可以很好的和jenkins集成。 2.安装Pytestpytest不是python默认的package，需要手动安装。其同时可以在windows、unix系统上安装。最新的pytest版本为5.4.1，pytest5.4.1支持Python 3.5、3.6、3.7版本。本书采取（书籍资料包中）的Python版本为Python3.7，因此可以与pytest结合使用。
打开windows系统的cmd命令窗口，在命令行中运行以下命令：
pip install -U pytest

安装进度，如图所示。

文章图片

::: hljs-center
图 pytest安装
:::
如仍然安装不成功，可以指定国内镜像，如国内的清华大学开源软件镜像站，地址是：https://mirrors.tuna.tsinghua.edu.cn/，命令如下：
pip install --index https://mirrors.ustc.edu.cn/pypi/web/simple/ pytest
安装进度，如下所示。

C:\\Windows\\system32> pip install --index https://mirrors.ustc.edu.cn/pypi/web/simple/ pytest Looking in indexes: https://mirrors.ustc.edu.cn/pypi/web/simple/ Collecting pytest Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/c7/e2/c19c667f42f72716a7d03e8dd4d6f63f47d39feadd44cc1ee7ca3089862c/pytest-5.4.1-py3-none-any.whl (246kB) |████████████████████████████████| 256kB 1.7MB/s Collecting pluggy< 1.0,> =0.12 (from pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/a0/28/85c7aa31b80d150b772fbe4a229487bc6644da9ccb7e427dd8cc60cb8a62/pluggy-0.13.1-py2.py3-none-any.whl Collecting colorama; sys_platform == "win32" (from pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/c9/dc/45cdef1b4d119eb96316b3117e6d5708a08029992b2fee2c143c7a0a5cc5/colorama-0.4.3-py2.py3-none-any.whl Collecting py> =1.5.0 (from pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/99/8d/21e1767c009211a62a8e3067280bfce76e89c9f876180308515942304d2d/py-1.8.1-py2.py3-none-any.whl (83kB) |████████████████████████████████| 92kB 2.0MB/s Collecting more-itertools> =4.0.0 (from pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/72/96/4297306cc270eef1e3461da034a3bebe7c84eff052326b130824e98fc3fb/more_itertools-8.2.0-py3-none-any.whl (43kB) |████████████████████████████████| 51kB 3.4MB/s Collecting packaging (from pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/62/0a/34641d2bf5c917c96db0ded85ae4da25b6cd922d6b794648d4e7e07c88e5/packaging-20.3-py2.py3-none-any.whl Collecting attrs> =17.4.0 (from pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/a2/db/4313ab3be961f7a763066401fb77f7748373b6094076ae2bda2806988af6/attrs-19.3.0-py2.py3-none-any.whl Collecting atomicwrites> =1.0; sys_platform == "win32" (from pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/52/90/6155aa926f43f2b2a22b01be7241be3bfd1ceaf7d0b3267213e8127d41f4/atomicwrites-1.3.0-py2.py3-none-any.whl Collecting importlib-metadata> =0.12; Python_version < "3.8" (from pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/8b/03/a00d504808808912751e64ccf414be53c29cad620e3de2421135fcae3025/importlib_metadata-1.5.0-py2.py3-none-any.whl Collecting wcwidth (from pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/58/b4/4850a0ccc6f567cc0ebe7060d20ffd4258b8210efadc259da62dc6ed9c65/wcwidth-0.1.8-py2.py3-none-any.whl Collecting six (from packaging-> pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/65/eb/1f97cb97bfc2390a276969c6fae16075da282f5058082d4cb10c6c5c1dba/six-1.14.0-py2.py3-none-any.whl Collecting pyparsing> =2.0.2 (from packaging-> pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/5d/bc/1e58593167fade7b544bfe9502a26dc860940a79ab306e651e7f13be68c2/pyparsing-2.4.6-py2.py3-none-any.whl (67kB) |████████████████████████████████| 71kB 4.8MB/s Collecting zipp> =0.5 (from importlib-metadata> =0.12; Python_version < "3.8"-> pytest) Downloading https://mirrors.tuna.tsinghua.edu.cn/pypi/web/packages/b2/34/bfcb43cc0ba81f527bc4f40ef41ba2ff4080e047acb0586b56b3d017ace4/zipp-3.1.0-py3-none-any.whl Installing collected packages: zipp, importlib-metadata, pluggy, colorama, py, more-itertools, six, pyparsing, packaging, attrs, atomicwrites, wcwidth, pytest Successfully installed atomicwrites-1.3.0 attrs-19.3.0 colorama-0.4.3 importlib-metadata-1.5.0 more-itertools-8.2.0 packaging-20.3 pluggy-0.13.1 py-1.8.1 pyparsing-2.4.6 pytest-5.4.1 six-1.14.0 wcwidth-0.1.8 zipp-3.1.0 WARNING: You are using pip version 19.2.3, however version 20.0.2 is available. You should consider upgrading via the Python -m pip install --upgrade pip command.

检查您是否安装了正确的版本
pytest--version。

C:\\Windows\\system32> pytest --version This is pytest version 5.4.1, imported from d:\\program files\\python37\\lib\\site-packages\\pytest\\__init__.py

Pytest帮助命令
pytest--help或pytest-h。

E:\\pytestDemo> pytest --help usage: pytest [options] [file_or_dir] [file_or_dir] [...]positional arguments: file_or_dirgeneral: -k EXPRESSIONonly run tests which match the given substring expression. An expression is a Python evaluatable expression where all names are substring-matched against test names and their parent classes. Example: -k test_method or test_other matches all test functions and classes whose name contains test_method or test_other, while -k not test_method matches those that dont contain test_method in their names. -k not test_method and not test_other will eliminate the matches. Additionally keywords are matched to classes and functions containing extra names in their extra_keyword_matches set, as well as functions which have names assigned directly to them. The matching is case-insensitive. -m MARKEXPRonly run tests matching given mark expression. example: -m mark1 and not mark2. --markersshow markers (builtin, plugin and per-project ones). -x, --exitfirstexit instantly on first error or failed test. --maxfail=numexit after first num failures or errors.

3.Pytest案例实战 3.1. pytest基础案例通过PyCharm在工程目录下，创建pytestDemo的Python package，Pytest的案例均存放在pytestDemo下。
pytest测试用例编写非常简单，pytest可以在不同的函数、包中发现用例，但pytest有如下约束。

文件名以test（如：test.py）开头或以_test（如： _test.py）结尾的py文件；
以test_开头的函数或test_开头的方法；
以Test开头的类，并且不能带有 init 方法；
要注意的是所有的包必须要有init.py文件(在PyCharm中会自动生成)。 3.1.1 创建基础待测方法
在pytestDemo下新建test_demo.py文件，代码如下：

def add(a,b): returna + b

def test_add():
assert add(2,3) == 5

### 3.1.2 运行测试方法通过cmd进入到test_demo.py所在的文件夹下，然后运行pytest，如下所示。

E:\\> cd pytestDemo
E:\\pytestDemo> pytest
================================================= test session starts =================================================
platform win32 -- Python 3.7.5, pytest-5.4.1, py-1.8.1, pluggy-0.13.1
rootdir: E:\\pytestDemo
collected 1 item
test_demo.py .[100%]
================================ 1 passed in 0.02s =============

将test_demo.py将代码进行变动，将实际值与期望值改成不一致，代码如下：

def add(a,b):
returna + b
def test_add():
assert add(2,3) == 6

cmd进入到test_demo.py所在的文件夹下，然后运行pytest，如下所示。

E:\\pytestDemo> pytest
======================= test session starts ===========================
platform win32 -- Python 3.7.5, pytest-5.4.1, py-1.8.1, pluggy-0.13.1
rootdir: E:\\pytestDemo
collected 1 item
testdemo.py F[100%]
======================= FAILURES =========================
____ test_add __
def test_add():
3.2. 测试用例存放在类中可将测试用例放在测试类中，通过执行测试类，而执行类中的测试用例。
3.2.1 优化测试代码
将test_demo.py将代码进行优化，代码如下：

def add(a, b): return a + bdef minus(a, b): return a - bclass TestClass: def test_add(self): assert add(2, 3) == 5def test_minus(self): assert minus(3, 2) == 2

3.2.2 运行优化后的测试方法
cmd进入到test_demo.py所在的文件夹下，然后运行pytest，结果如下所示。

E:\\pytestDemo> pytest ===================== test session starts ========================== platform win32 -- Python 3.7.5, pytest-5.4.1, py-1.8.1, pluggy-0.13.1 rootdir: E:\\pytestDemo collected 2 items test_demo.py .F[100%] =================== FAILURES ========================= ___________________ TestClass.test_minus _______________________________ self = < pytestDemo.test_demo.TestClass object at 0x0000023E3C369FC8> def test_minus(self): > assert minus(3, 2) == 2 Eassert 1 == 2 E+where 1 = minus(3, 2)test_demo.py:27: AssertionError ===================== short test summary info =========== FAILED test_demo.py::TestClass::test_minus - assert 1 == 2 =============== 1 failed, 1 passed in 0.06s ==============================

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