Time will tell.
Pytest 是 Python 最流行的单元测试框架之一，帮助更便捷的编写测试脚本， 并支持多种功能复杂的测试场景， 能用来做app测试也能用作函数测试。
一、Pytest 优点
- 允许使用 assert 进行断言
- 自动识别测试脚本、类、函数
- 可用于管理小型或者参数类型的测试数据或资源
- 兼容 unittest 和 nose 测试框架
- 支持 Python2.7/Python3.4+
- 丰富的插件支持，超过315个插件支持
二、Pytest 安装
pip install -U pytest
如果提示下面的错误，说明是pip的版本太老了，要更新下：
Could not find a version that satisfies the requirement pytest (from versions: )
No matching distribution found for pytest
更新方式：
easy_install --upgrade pip
三、官方示例
准备一个test_sample.py内容如下：
def inc(x):
return x + 1
def test_answer():
assert inc(3) == 5
在文件所在目录执行：
pytest
做下说明：
pytest脚本都以test_xxx.py为文件名；
inc方法是我们定义的一个自增函数，该函数将传递进来的参数加1后返回；
test_answer是我们编写的一个测试函数，其中我们使用基本的断言语句assert来对结果进行验证，测试函数以test_xxx作为命名。
执行结果如下：
============================================================ test session starts ============================================================
platform darwin -- Python 2.7.15, pytest-4.1.0, py-1.7.0, pluggy-0.8.0
rootdir: /Users/jackey/Documents/iOS/code/iOS-Auto/Agent_Test, inifile:
collected 1 item
test_sample.py F [100%]
================================================================= FAILURES ==================================================================
________________________________________________________________ test_answer ________________________________________________________________
def test_answer():
> assert inc(3) == 5
E assert 4 == 5
E + where 4 = inc(3)
test_sample.py:5: AssertionError
========================================================= 1 failed in 0.05 seconds ==========================================================
(wda_python) bash-3.2$
当执行到 assert inc(3) == 5 时，报错。
执行pytest会在当前目录和子目录中寻找test_xx.py的测试文件，并进入到测试文件中寻找test_xx开头的测试函数开始执行
执行pytest -q test_xxx.py是执行执行的脚本
在看一个例子,测试指定错误： (Assert that a certain exception is raised)
import pytest
def f():
raise SystemExit(1)
def test_mytest():
with pytest.raises(SystemExit):
f()
执行指令：
pytest -q test_sysexit.py
输出：
(wda_python) bash-3.2$ pytest -q test_sysexit.py
. [100%]
1 passed in 0.04 seconds
(wda_python) bash-3.2$
如果要开发多个测试方法，可以把方法写进一个class中：
class TestClass(object):
def test_one(self):
x = 'this'
assert 'h' in x
def test_two(self):
x = 'hello'
assert hasattr(x, 'check')
Pytest 能够自动识别类中的测试方法， 也不用我们去创建子类或者实实例, 运行结果如下：
(wda_python) bash-3.2$ pytest -q test_sample.py
.F [100%]
================================================================== FAILURES ==================================================================
_____________________________________________________________ TestClass.test_two _____________________________________________________________
self = <test_sample.TestClass object at 0x102e151d0>
def test_two(self):
x = 'hello'
> assert hasattr(x, 'check')
E AssertionError: assert False
E + where False = hasattr('hello', 'check')
test_sample.py:8: AssertionError
1 failed, 1 passed in 0.08 seconds
(wda_python) bash-3.2$
除了直接在脚本路径执行pytest外， 还可以用以下方式：
python -m pytest xxx.py
出现第一个（或第N个）错误时停止：
pytest -x # stop after first failure
pytest --maxfail=2 # stop after two failures
运行执行测试脚本：
pytest test_mod.py
运行指定目录下的所有脚本：
pytest testing/
运行包含指定关键字的测试方法, 可以是文件名、类名、测试函数名
pytest -k "MyClass and not method"
执行node id运行测试脚本，每一个被收集的测试方法都会分配一个指定的id， 我们可以用一下方式运行执行的测试方法：
# To run a specific test within a module
pytest test_mod.py::test_func
# To run a test within a class
pytest test_mod.py::TestClass::test_method
日志打印的不同方式：
pytest --showlocals # show local variables in tracebacks
pytest -l # show local variables (shortcut)
pytest --tb=auto # (default) 'long' tracebacks for the first and last
# entry, but 'short' style for the other entries
pytest --tb=long # exhaustive, informative traceback formatting
pytest --tb=short # shorter traceback format
pytest --tb=line # only one line per failure
pytest --tb=native # Python standard library formatting
pytest --tb=no # no traceback at all
四、测试报告
pytest 默认是完整的测试报告， 我们可以加上-r标签显示简短测试报告，可再搭配一下参数。
Here is the full list of available characters that can be used:
f - failed
E - error
s - skipped
x - xfailed
X - xpassed
p - passed
P - passed with output
a - all except pP
可以多个参数一起使用
Debug模式
pytest --pdb
示例：
(wda_python) bash-3.2$ pytest --pdb
========================================================== test session starts ===========================================================
platform darwin -- Python 2.7.15, pytest-4.1.0, py-1.7.0, pluggy-0.8.0
rootdir: /Users/jackey/Documents/iOS/code/iOS-Auto/Agent_Test, inifile:
collected 3 items
test_sample.py .F
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> traceback >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
self = <test_sample.TestClass object at 0x10e928610>
def test_two(self):
x = 'hello'
> assert hasattr(x, 'check')
E AssertionError: assert False
E + where False = hasattr('hello', 'check')
test_sample.py:8: AssertionError
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> entering PDB >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> /Users/jackey/Documents/iOS/code/iOS-Auto/Agent_Test/test_sample.py(8)test_two()
-> assert hasattr(x, 'check')
(Pdb) print x
hello
(Pdb) print hasattr(x,'check')
False
(Pdb)
还可以指定第几次失败开始进入debug：
pytest -x --pdb # drop to PDB on first failure, then end test session
pytest --pdb --maxfail=3 # drop to PDB for first three failures
任何失败的异常信息都会存储在sys.last_value，sys.last_type以及 sys_last_traceback。
在debug中可以通过以下方式获取最后报错的内容。
(Pdb) import sys
(Pdb) sys.last_traceback.tb_lineno
1357
(Pdb) sys.last_value
AssertionError(u"assert False\n + where False = hasattr('hello', 'check')",)
(Pdb)
在执行一开始就进入到debug模式
pytest --trace
输入next执行下一步，exit退出。
脚本中设置断点
import pdb
pdb.set_trace()
例如：
import pdb
class TestClass(object):
def test_one(self):
x = 'this'
pdb.set_trace()
assert 'h' in x
def test_two(self):
x = 'hello'
assert hasattr(x, 'check')
获取执行最慢的n个测试步骤：
pytest --durations=10
但如果所有脚本的运行时间都小于0.01s, 就不显示了， 除非带上-vv参数
pytest --durations=10 -vv
输出结果：
======================================================= slowest 10 test durations ========================================================
0.00s call test_sample.py::TestClass::test_two
0.00s setup test_sysexit.py::test_mytest
0.00s setup test_sample.py::TestClass::test_two
0.00s setup test_sample.py::TestClass::test_one
0.00s teardown test_sample.py::TestClass::test_two
0.00s teardown test_sample.py::TestClass::test_one
0.00s call test_sysexit.py::test_mytest
0.00s teardown test_sysexit.py::test_mytest
0.00s call test_sample.py::TestClass::test_one
=================================================== 1 failed, 2 passed in 0.06 seconds ===================================================
(wda_python) bash-3.2$
将日志保存到指定文件
pytest --resultlog=path
我们也可以在 pytestdemo 脚本中去启动pytest：
import pytest
pytest.main()
执行python pytestdemo.py就可以执行pytest，main()不会抛出SystemExit的异常, 但会返回exitcode，一共有6种exitcode。
Exit code 0: All tests were collected and passed successfully
Exit code 1: Tests were collected and run but some of the tests failed
Exit code 2: Test execution was interrupted by the user
Exit code 3: Internal error happened while executing tests
Exit code 4: pytest command line usage error
Exit code 5: No tests were collected
我们试着加上打印
import pytest
print pytest.main()
输出：
(wda_python) bash-3.2$ python pytestDemo.py
========================================================== test session starts ===========================================================
platform darwin -- Python 2.7.15, pytest-4.1.0, py-1.7.0, pluggy-0.8.0
rootdir: /Users/jackey/Documents/iOS/code/iOS-Auto/Agent_Test, inifile:
collected 3 items
test_sample.py .F [ 66%]
test_sysexit.py . [100%]
================================================================ FAILURES ================================================================
___________________________________________________________ TestClass.test_two ___________________________________________________________
self = <test_sample.TestClass object at 0x1038ba650>
def test_two(self):
x = 'hello'
> assert hasattr(x, 'check')
E AssertionError: assert False
E + where False = hasattr('hello', 'check')
test_sample.py:11: AssertionError
=================================================== 1 failed, 2 passed in 0.05 seconds ===================================================
1
(wda_python) bash-3.2$
我们还可以在main中传递参数：
pytest.main(['-q','test_sample.py'])
给pytest.main添加plugin,，如下示例在执行的开头和结尾， 添加打印信息。
import pytest
class MyPlugin(object):
def pytest_sessionfinish(self):
print '*** Test run reporting finishing'
def pytest_sessionstart(self):
print '*** Test run report beginning'
pytest.main(['-q','test_sample.py'], plugins=[MyPlugin()])
输出：
(wda_python) bash-3.2$ python pytestDemo.py
*** Test run report beginning
.F [100%]*** Test run reporting finishing
================================================================ FAILURES ================================================================
___________________________________________________________ TestClass.test_two ___________________________________________________________
self = <test_sample.TestClass object at 0x1090843d0>
def test_two(self):
x = 'hello'
> assert hasattr(x, 'check')
E AssertionError: assert False
E + where False = hasattr('hello', 'check')
test_sample.py:11: AssertionError
1 failed, 1 passed in 0.05 seconds
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