成熟全功能的python测试工具
支持posix / windows， python的2.5-3.3 ， pypy和jython - 2.5.1
1000测试用例自测零bug。
pytest升级时有很好的向后兼容性
丰富的在线和pdf文档
大量的第三方插件和内置帮助
在许多小型和大型项目和组织使用
许多测试实例
灵活
易学，有多种用法
assert语句断言
追踪和失败断言报告
打印调试和测试执行期间可以捕获标准输出
适合简单的单元测试到复杂的功能测试
模块化和参数化的平台
参数化的测试函数
支持属性
skip和xfail处理失败的用例
xdist插件分发测试给多个cpu
不断地重新运行失败的测试
灵活的python测试发现
集成
多范式：可以执行nose, unittest 和doctest风格的测试用例，甚至django和trial。
支持良好的集成实践
支持扩展的xunit风格setup
支持非python测试
支持生成测试覆盖率报告
支持pep8兼容的编码风格
扩展插件和定制系统：
所有的收集，报告，运行方面都委派给hook函数
定制可以是每个目录，每个项目或每个pypi上发布的插件
很容易添加命令行选项或定制现有的行为
安装
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">1 pip install -u pytest # or 2 easy_install -u pytest</pre>
检查版本：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">1 # py.test --version 2 this is pytest version 2.5.2, imported from /usr/lib/python2.7/site-packages/pytest.pyc</pre>
第一个实例：
代码：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">1 # content of test_sample.py
2 def func(x): 3 return x + 1
4 def test_answer(): 5 assert func(3) == 5</pre>
执行结果：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;"> 1 # py.test
2 =========================================================================================================== test session starts ===========================================================================================================
3 platform linux2 -- python 2.7.3 -- py-1.4.20 -- pytest-2.5.2
4 collected 1 items 5
6 test_sample.py f
7
8 ================================================================================================================ failures =================================================================================================================
9 _______________________________________________________________________________________________________________ test_answer _______________________________________________________________________________________________________________ 10
11 def test_answer(): 12 > assert func(3) == 5
13 e assert 4 == 5
14 e + where 4 = func(3) 15
16 test_sample.py:8: assertionerror 17 ======================================================================================================== 1 failed in 0.34 seconds =========================================================================================================</pre>
pytest通过标准测试发现规则发现test_answer函数，通常是查找 test_前缀。我们得到了一个故障报告，因为我们调用func(3)没有返回5。pytest的高级內省断言会智能报告assert的中间值，不需要记住那些junit传统方法。
异常断言
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">1 import pytest 2 def f(): 3 raise systemexit(1) 4 def test_mytest(): 5 with pytest.raises(systemexit): 6 f()</pre>
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">1 $ py.test -q test_sysexit.py 2 . 3 1 passed in 0.01 seconds</pre>
-q表示静默模式：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">1 -q, --quiet decrease verbosity.</pre>
在类中分组用例
代码
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">1 # content of test_class.py
2 class testclass: 3 def test_one(self): 4 x = "this"
5 assert 'h' in x 6
7 def test_two(self): 8 x = "hello"
9 assert hasattr(x, 'check')</pre>
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;"> 1 # py.test test_class.py
4 collected 2 items 5
6 test_class.py .f
9 ___________________________________________________________________________________________________________ testclass.test_two ____________________________________________________________________________________________________________ 10
11 self = <test_class.testclass instance at 0x265aef0>
12
13 def test_two(self): 14 x = "hello"
15 > assert hasattr(x, 'check') 16 e assert hasattr('hello', 'check') 17
18 test_class.py:12: assertionerror 19 =================================================================================================== 1 failed, 1 passed in 0.01 seconds ====================================================================================================</pre>
功能测试示例：生成唯一的临时目录
功能测试经常需要创建一些文件，并将其传递给应用程序对象。pytest提供 builtin fixtures/function 参数允许请求任意资源，例如唯一的临时目录：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">1 def test_needsfiles(tmpdir): 2 print tmpdir 3 assert 0</pre>
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;"> 1 ]# py.test -q test_tmpdir.py
2 ff
3 ================================================================================================================ failures =================================================================================================================
4 _____________________________________________________________________________________________________________ test_needsfiles _____________________________________________________________________________________________________________
5
6 tmpdir = local('/tmp/pytest-0/test_needsfiles0')
8 def test_needsfiles(tmpdir):
9 print tmpdir 10 > assert 0
11 e assert 0
13 test_tmpdir.py:7: assertionerror 14 ------------------------------------------------------------------------------------------------------------- captured stdout -------------------------------------------------------------------------------------------------------------
15 /tmp/pytest-0/test_needsfiles0 16 1 failed in 0.07 seconds</pre>
断言的前面的print内容也会打印出来，测试时可以多加print语句，保证异常时输出一些有用的信息。
下面方式可以查看内置的
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;"> 1 # py.test --fixtures
2
3 =========================================================================================================== test session starts ===========================================================================================================
4 platform linux2 -- python 2.7.3 -- py-1.4.20 -- pytest-2.5.2
5 collected 5 items 6 capsys
7 enables capturing of writes to sys.stdout/sys.stderr and makes
8 captured output available via <code>capsys.readouterr()</code> method calls
9 which return a <code>(out, err)</code> tuple. 10
11 capfd 12 enables capturing of writes to file descriptors 1 and 2 and makes 13 captured output available via <code>capsys.readouterr()</code> method calls 14 which return a <code>(out, err)</code> tuple. 15
16 monkeypatch 17 the returned <code>monkeypatch</code> funcarg provides these 18 helper methods to modify objects, dictionaries or os.environ:: 19
20 monkeypatch.setattr(obj, name, value, raising=true) 21 monkeypatch.delattr(obj, name, raising=true) 22 monkeypatch.setitem(mapping, name, value) 23 monkeypatch.delitem(obj, name, raising=true) 24 monkeypatch.setenv(name, value, prepend=false) 25 monkeypatch.delenv(name, value, raising=true) 26 monkeypatch.syspath_prepend(path) 27 monkeypatch.chdir(path) 28
29 all modifications will be undone after the requesting 30 test function has finished. the <code>raising</code> 31 parameter determines if a keyerror or attributeerror 32 will be raised if the set/deletion operation has no target. 33
34 pytestconfig 35 the pytest config object with access to command line opts. 36 recwarn 37 return a warningsrecorder instance that provides these methods: 38
39 * <code>pop(category=none)</code>: return last warning matching the category. 40 * <code>clear()</code>: clear list of warnings 41
42 see http://docs.python.org/library/warnings.html for information
43 on warning categories. 44
45 tmpdir 46 return a temporary directory path object
47 which is unique to each test function invocation, 48 created as a sub directory of the base temporary 49 directory. the returned object is a <code>py.path.local</code>_ 50 path object. 51
52
53 ============================================================================================================ in 0.02 seconds =============================================================================================================</pre>
python -m pytest调用：
python -m pytest [...] 效果和py.test [...] 一样
获取版本，选项名，环境变量
py.test --version 看版本
py.test --fixtures 查看内置参数
py.test -h | --help 命令行和配置文件帮助
失败后停止
首次失败后停止执行：py.test -x
py.test --maxfail=2 两次失败之后停止执行
执行选择用例
py.test test_mod.py，执行模块中的用例
py.test somepath，执行路径中用例
py.test -k stringexpr，执行字符串表达式中的用例，比如"myclass? and not method"，选择testmyclass.test_something，排除了testmyclass.test_method_simple。
py.test --pyargs pkg，导入pkg，使用其文件系统位置来查找和执行用例。执行pypkg目录下的所有用例。
调试输出：
py.test --showlocals 在traceback中显示本地变量
py.test -l 在traceback中显示本地变量（快捷方式）
py.test --tb=long 默认的traceback信息格式化形式
py.test --tb=native 标准库格式化形式
py.test --tb=short 更短的格式
py.test --tb=line 每个错误一行
失败时调用pdb (python debugger)：
python带有一个内置的python调试器称为pdb。pytest可以在命令行选项指定调用：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test --pdb </pre>
这将每次失败时调用python调试器。
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test -x --pdb # 失败时调用pdb，然后退出测试。
py.test --pdb - maxfail=3＃ 前3次失败调用pdb。 </pre>
设置断点：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">1 import pytest 2 def test_function(): 3 ... 4 pytest.set_trace() # invoke pdb debugger and tracing</pre>
以前的版本中只有通过py.test-s禁用命令行捕捉才可以进入pdb调试。
profiling测试执行时间：得到最执行慢的10个测试：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test --durations=10 </pre>
创建junitxml格式的文件
创建hudson或其他持续集成服务器的结果文件：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test --junitxml=path </pre>
创建resultlog格式的文件
要创建纯文本的机器可读的结果文件，用于pypy-testweb展示等。
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test --resultlog=path </pre>
发送测试报告给在线pastebin服务
bpaste可以为你的文本生成url连接，下面为创建每个测试失败创建一个url：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test --pastebin=failed
py.test --pastebin=all
py.test --pastebin=failed -x </pre>
目前只支持：py.test --pastebin=failed
禁用插件
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test -p no:doctest </pre>
在python代码中调用pytest
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">1 $ python myinvoke.py 2 ***
3 test run reporting finishing</pre>
使用虚拟环境
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;"> 1 #virtualenv .
2 new python executable in ./bin/python
3 installing setuptools, pip...done.
4 root@autotest:[/data/code/python/pytest]#source bin/activate
5 (pytest)root@autotest:[/data/code/python/pytest]#pip install pytest 6 downloading/unpacking pytest
7 downloading pytest-2.5.2.tar.gz (608kb): 608kb downloaded
8 running setup.py (path:/data/code/python/pytest/build/pytest/setup.py) egg_info for package pytest 9
10 downloading/unpacking py>=1.4.20 (from pytest) 11 downloading py-1.4.22.tar.gz (189kb): 189kb downloaded 12 running setup.py (path:/data/code/python/pytest/build/py/setup.py) egg_info for package py 13
14 installing collected packages: pytest, py 15 running setup.py install for pytest 16
17 installing py.test-2.7 script to /data/code/python/pytest/bin 18 installing py.test script to /data/code/python/pytest/bin 19 running setup.py install for py 20
21 successfully installed pytest py 22 cleaning up...</pre>
测试布局和导入规则
测试布局的方法有2种。一为放置在应用代码之外，适用于有很多功能测试等情况。
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "courier new" !important; font-size: 12px !important;">setup.py # your distutils/setuptools python package metadata
mypkg/ init.py
appmodule.py
tests/ test_app.py
...</pre>
二为嵌入测试目录到应用，当(单元)测试和应用之间的有直接关系，并想一起发布时有用：
...
test/ test_app.py
http://automationtesting.sinaapp.com/blog/m_pytest_doc1
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