成熟全功能的python測試工具
支援posix / windows， python的2.5-3.3 ， pypy和jython - 2.5.1
1000測試用例自測零bug。
pytest更新時有很好的向後相容性
豐富的線上和pdf文檔
大量的第三方插件和内置幫助
在許多小型和大型項目群組織使用
許多測試執行個體
靈活
易學，有多種用法
assert語句斷言
追蹤和失敗斷言報告
列印調試和測試執行期間可以捕獲标準輸出
适合簡單的單元測試到複雜的功能測試
子產品化和參數化的平台
參數化的測試函數
支援屬性
skip和xfail處理失敗的用例
xdist插件分發測試給多個cpu
不斷地重新運作失敗的測試
靈活的python測試發現
內建
多範式：可以執行nose, unittest 和doctest風格的測試用例，甚至django和trial。
支援良好的內建實踐
支援擴充的xunit風格setup
支援非python測試
支援生成測試覆寫率報告
支援pep8相容的編碼風格
擴充插件和定制系統：
所有的收集，報告，運作方面都委派給hook函數
定制可以是每個目錄，每個項目或每個pypi上釋出的插件
很容易添加指令行選項或定制現有的行為
安裝
<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>
檢查版本：
<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>
第一個執行個體：
代碼：
<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>
執行結果：
<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通過标準測試發現規則發現test_answer函數，通常是查找 test_字首。我們得到了一個故障報告，因為我們調用func(3)沒有傳回5。pytest的進階內省斷言會智能報告assert的中間值，不需要記住那些junit傳統方法。
異常斷言
<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表示靜默模式：
<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>
在類中分組用例
代碼
<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>
功能測試示例：生成唯一的臨時目錄
功能測試經常需要建立一些檔案，并将其傳遞給應用程式對象。pytest提供 builtin fixtures/function 參數允許請求任意資源，例如唯一的臨時目錄：
<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>
斷言的前面的print内容也會列印出來，測試時可以多加print語句，保證異常時輸出一些有用的資訊。
下面方式可以檢視内置的
<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調用：
python -m pytest [...] 效果和py.test [...] 一樣
擷取版本，選項名，環境變量
py.test --version 看版本
py.test --fixtures 檢視内置參數
py.test -h | --help 指令行和配置檔案幫助
失敗後停止
首次失敗後停止執行：py.test -x
py.test --maxfail=2 兩次失敗之後停止執行
執行選擇用例
py.test test_mod.py，執行子產品中的用例
py.test somepath，執行路徑中用例
py.test -k stringexpr，執行字元串表達式中的用例，比如"myclass? and not method"，選擇testmyclass.test_something，排除了testmyclass.test_method_simple。
py.test --pyargs pkg，導入pkg，使用其檔案系統位置來查找和執行用例。執行pypkg目錄下的所有用例。
調試輸出：
py.test --showlocals 在traceback中顯示本地變量
py.test -l 在traceback中顯示本地變量（快捷方式）
py.test --tb=long 預設的traceback資訊格式化形式
py.test --tb=native 标準庫格式化形式
py.test --tb=short 更短的格式
py.test --tb=line 每個錯誤一行
失敗時調用pdb (python debugger)：
python帶有一個内置的python調試器稱為pdb。pytest可以在指令行選項指定調用：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test --pdb </pre>
這将每次失敗時調用python調試器。
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test -x --pdb # 失敗時調用pdb，然後退出測試。
py.test --pdb - maxfail=3＃ 前3次失敗調用pdb。 </pre>
設定斷點：
<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>
以前的版本中隻有通過py.test-s禁用指令行捕捉才可以進入pdb調試。
profiling測試執行時間：得到最執行慢的10個測試：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test --durations=10 </pre>
建立junitxml格式的檔案
建立hudson或其他持續內建伺服器的結果檔案：
<pre style="margin-top: 0px; margin-bottom: 0px; white-space: pre-wrap; word-wrap: break-word;">py.test --junitxml=path </pre>
建立resultlog格式的檔案
要建立純文字的機器可讀的結果檔案，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>
發送測試報告給線上pastebin服務
bpaste可以為你的文本生成url連接配接，下面為建立每個測試失敗建立一個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>
目前隻支援：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代碼中調用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>
使用虛拟環境
<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>
測試布局和導入規則
測試布局的方法有2種。一為放置在應用代碼之外，适用于有很多功能測試等情況。
<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>
二為嵌入測試目錄到應用，當(單元)測試和應用之間的有直接關系，并想一起釋出時有用：
...
test/ test_app.py
http://automationtesting.sinaapp.com/blog/m_pytest_doc1
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