Python开发单元测试,必不可少

时间：2020-03-19 17:59:45 阅读：54 评论：0 收藏：0 [点我收藏+]

先介绍一下Python的单元测试常用框架

unittest
pytest
nose

下面重点介绍pytest

1. 概述

pytest是一个非常成熟的全功能的Python测试框架，主要特点有以下几点：

1、简单灵活，容易上手，文档丰富；
2、支持参数化，可以细粒度地控制要测试的测试用例；
3、能够支持简单的单元测试和复杂的功能测试，还可以用来做selenium/appnium等自动化测试、接口自动化测试（pytest+requests）;
4、pytest具有很多第三方插件，并且可以自定义扩展，比较好用的如pytest-selenium（集成selenium）、pytest-html（完美html测试报告生成）、pytest-rerunfailures（失败case重复执行）、pytest-xdist（多CPU分发）等；
5、测试用例的skip和xfail处理；
6、可以很好的和CI工具结合，例如jenkins

2. 使用介绍

2.1. 安装

pip install pytest

2.2. 示例代码

编写规则

编写pytest测试样例非常简单，只需要按照下面的规则：

测试文件以test_开头（以_test结尾也可以）
测试类以Test开头，并且不能带有 init 方法
测试函数以test_开头
断言使用基本的assert即可

pytest1.py

# -*- coding:utf-8 -*-
import pytest

@pytest.fixture(scope=‘function‘)
def setup_function(request):
    def teardown_function():
        print("teardown_function called.")
    request.addfinalizer(teardown_function)  # 此内嵌函数做teardown工作
    print(‘setup_function called.‘)

@pytest.fixture(scope=‘module‘)
def setup_module(request):
    def teardown_module():
        print("teardown_module called.")
    request.addfinalizer(teardown_module)
    print(‘setup_module called.‘)

@pytest.mark.website
def test_1(setup_function):
    print(‘Test_1 called.‘)

def test_2(setup_module):
    print(‘Test_2 called.‘)

fixture的scope参数

scope参数有四种，分别是‘function‘,‘module‘,‘class‘,‘session‘，默认为function。

function：每个test都运行，默认是function的scope
class：每个class的所有test只运行一次
module：每个module的所有test只运行一次
session：每个session只运行一次

setup和teardown操作

setup，在测试函数或类之前执行，完成准备工作，例如数据库链接、测试数据、打开文件等
teardown，在测试函数或类之后执行，完成收尾工作，例如断开数据库链接、回收内存资源等
备注：也可以通过在fixture函数中通过yield实现setup和teardown功能

2.3. 测试结果

如何执行

pytest # run all tests below current dir
pytest test_mod.py # run tests in module file test_mod.py
pytest somepath # run all tests below somepath like ./tests/
pytest -k stringexpr # only run tests with names that match the
# the "string expression", e.g. "MyClass and not method"
# will select TestMyClass.test_something
# but not TestMyClass.test_method_simple
pytest test_mod.py::test_func # only run tests that match the "node ID",
# e.g "test_mod.py::test_func" will be selected
# only run test_func in test_mod.py

通过pytest.mark对test方法分类执行

通过@pytest.mark控制需要执行哪些feature的test，例如在执行test前增加修饰@pytest.mark.website

通过 -m "website" 执行有website标记的test方法

$ pytest  -v -m "website" pytest1.py
============================================================================== test session starts ===============================================================================
platform linux2 -- Python 2.7.14, pytest-3.0.0, py-1.5.2, pluggy-0.3.1 -- /home/kevin/soft/anaconda2/bin/python
cachedir: .cache
Using --randomly-seed=1522925202
rootdir: /home/kevin/learn/python-web/tox/case2, inifile:
plugins: randomly-1.0.0, mock-1.2, cov-2.0.0
collected 3 items

pytest1.py::test_1 PASSED

============================================================================= pytest-warning summary =============================================================================
WC1 None pytest_funcarg__cov: declaring fixtures using "pytest_funcarg__" prefix is deprecated and scheduled to be removed in pytest 4.0.  Please remove the prefix and use the @pytest.fixture decorator instead.
=============================================================================== 2 tests deselected ===============================================================================
=========================================================== 1 passed, 2 deselected, 1 pytest-warnings in 0.00 seconds ============================================================

通过 -m "not website" 执行没有website标记的test方法

$ pytest  -v -m "not website" pytest1.py
============================================================================== test session starts ===============================================================================
platform linux2 -- Python 2.7.14, pytest-3.0.0, py-1.5.2, pluggy-0.3.1 -- /home/kevin/soft/anaconda2/bin/python
cachedir: .cache
Using --randomly-seed=1522925192
rootdir: /home/kevin/learn/python-web/tox/case2, inifile:
plugins: randomly-1.0.0, mock-1.2, cov-2.0.0
collected 3 items

pytest1.py::test_3 PASSED
pytest1.py::test_2 PASSED

============================================================================= pytest-warning summary =============================================================================
WC1 None pytest_funcarg__cov: declaring fixtures using "pytest_funcarg__" prefix is deprecated and scheduled to be removed in pytest 4.0.  Please remove the prefix and use the @pytest.fixture decorator instead.
=============================================================================== 1 tests deselected ===============================================================================
=========================================================== 2 passed, 1 deselected, 1 pytest-warnings in 0.00 seconds ============================================================

Console参数介绍

-v 用于显示每个测试函数的执行结果
-q 只显示整体测试结果
-s 用于显示测试函数中print()函数输出
-x, --exitfirst, exit instantly on first error or failed test
-h 帮助

Case 1

$ pytest -v pytest1.py
============================================================================== test session starts ===============================================================================
platform linux2 -- Python 2.7.14, pytest-3.0.0, py-1.5.2, pluggy-0.3.1 -- /home/kevin/soft/anaconda2/bin/python
cachedir: .cache
Using --randomly-seed=1522920341
rootdir: /home/kevin/learn/python-web/tox/case2, inifile:
plugins: randomly-1.0.0, mock-1.2, cov-2.0.0
collected 3 items

pytest1.py::test_1 PASSED
pytest1.py::test_3 PASSED
pytest1.py::test_2 PASSED

============================================================================= pytest-warning summary =============================================================================
WC1 None pytest_funcarg__cov: declaring fixtures using "pytest_funcarg__" prefix is deprecated and scheduled to be removed in pytest 4.0.  Please remove the prefix and use the @pytest.fixture decorator instead.
================================================================== 3 passed, 1 pytest-warnings in 0.01 seconds ===================================================================

Case 2

$ pytest -s pytest1.py
============================================================================== test session starts ===============================================================================
platform linux2 -- Python 2.7.14, pytest-3.0.0, py-1.5.2, pluggy-0.3.1
Using --randomly-seed=1522920508
rootdir: /home/kevin/learn/python-web/tox/case2, inifile:
plugins: randomly-1.0.0, mock-1.2, cov-2.0.0
collected 3 items

pytest1.py setup_function called.
Test_1 called.
.teardown_function called.
setup_module called.
Test_2 called.
.Test_3 called.
.teardown_module called.


============================================================================= pytest-warning summary =============================================================================
WC1 None pytest_funcarg__cov: declaring fixtures using "pytest_funcarg__" prefix is deprecated and scheduled to be removed in pytest 4.0.  Please remove the prefix and use the @pytest.fixture decorator instead.
================================================================== 3 passed, 1 pytest-warnings in 0.01 seconds ===================================================================

3. 扩展插件

3.1. 测试报告

安装与样例

pip install pytest-cov # 计算pytest覆盖率，支持输出多种格式的测试报告
pytest --cov-report=html --cov=./ test_code_target_dir

Console参数介绍

--cov=[path], measure coverage for filesystem path (multi-allowed), 指定被测试对象，用于计算测试覆盖率
--cov-report=type, type of report to generate: term, term-missing, annotate, html, xml (multi-allowed), 测试报告的类型
--cov-config=path, config file for coverage, default: .coveragerc, coverage配置文件
--no-cov-on-fail, do not report coverage if test run fails, default: False，如果测试失败，不生成测试报告
--cov-fail-under=MIN, Fail if the total coverage is less than MIN. 如果测试覆盖率低于MIN，则认为失败

Console Result

---------------------------------------------------------------- coverage: platform linux2, python 2.7.14-final-0 ----------------------------------------------------------------
Name         Stmts   Miss  Cover
--------------------------------
pytest1.py      18      0   100%