Pytest编写测试函数

一个规范的测试方法一定带有断言，在使用pytest时，可以直接使用Python自带的assert关键字

Pytest允许在assert关键字添加任意表达式，表达式的值通过bool转换后等于False则表示断言失败，测试用例执行失败；如果等于True则表示断言成功，测试用例执行成功。

重写assertpytest

可以重写assert关键字，它可以截断对原生assert的调用，替换为pytest定义的assert，从而展示更详细的信息和细节。

from collections import namedtuple

Task = namedtuple('Task', ['summary','owner','done','id'])

# __new__.__defaults__创建默认的Task对象

Task.__new__.__defaults__ = (None, None, False, None)

import pytest

def test_task_equality():

    t1 = Task('sit there', 'brain')

    t2 = Task('do something', 'okken')

    print(t1)

    print(t2)

    assert t1 == t2

def test_dict_equal():

    t1_dict = Task('make sandwich', 'okken')._asdict()

    t2_dict = Task('make sandwich', 'okkem')._asdict()

    print(t1_dict)

    print(t2_dict)

    assert t1_dict == t2_dict

执行结果如下：

E:\Programs\Python\Python_Pytest\TestScripts>pytest test_three.py

======================= test session starts ==========================

platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0

rootdir: E:\Programs\Python\Python_Pytest\TestScripts

plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3

collected 2 items                                                                                                                                                          

test_three.py FF                                                                                                                                                     [100%]

===================== FAILURES ==================================

_____________________ test_task_equality _______________________________

    def test_task_equality():

        t1 = Task('sit there', 'brain')

        t2 = Task('do something', 'okken')

        print(t1)

        print(t2)

>       assert t1 == t2

E       AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None)

E         At index 0 diff: 'sit there' != 'do something'

E         Use -v to get the full diff

test_three.py:14: AssertionError

-------------------- Captured stdout call ----------------------------------------

Task(summary='sit there', owner='brain', done=False, id=None)

Task(summary='do something', owner='okken', done=False, id=None)

________________ test_dict_equal ______________________________

    def test_dict_equal():

        t1_dict = Task('make sandwich', 'okken')._asdict()

        t2_dict = Task('make sandwich', 'okkem')._asdict()

        print(t1_dict)

        print(t2_dict)

>       assert t1_dict == t2_dict

E       AssertionError: assert OrderedDict([...('id', None)]) == OrderedDict([(...('id', None)])

E         Omitting 3 identical items, use -vv to show

E         Differing items:

E         {'owner': 'okken'} != {'owner': 'okkem'}

E         Use -v to get the full diff

test_three.py:22: AssertionError

------------------------------- Captured stdout call --------------------------------------------

OrderedDict([('summary', 'make sandwich'), ('owner', 'okken'), ('done', False), ('id', None)])

OrderedDict([('summary', 'make sandwich'), ('owner', 'okkem'), ('done', False), ('id', None)])

================ 2 failed in 0.20 seconds=============================

加上参数-v，执行结果如下：

E:\Programs\Python\Python_Pytest\TestScripts>pytest test_three.py -v

================= test session starts ===============================

platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 -- c:\python37\python.exe

cachedir: .pytest_cache

rootdir: E:\Programs\Python\Python_Pytest\TestScripts

plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3

collected 2 items                                                                                                                                                          

test_three.py::test_task_equality FAILED                                                                                                                             [ 50%]

test_three.py::test_dict_equal FAILED                                                                                                                                [100%]

==================== FAILURES =========================

____________________ test_task_equality ________________________

    def test_task_equality():

        t1 = Task('sit there', 'brain')

        t2 = Task('do something', 'okken')

        print(t1)

        print(t2)

>       assert t1 == t2

E       AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None)

E         At index 0 diff: 'sit there' != 'do something'

E         Full diff:

E         - Task(summary='sit there', owner='brain', done=False, id=None)

E         ?                ^^^  ^^^          ^^^^

E         + Task(summary='do something', owner='okken', done=False, id=None)

E         ?               +++ ^^^  ^^^          ^^^^

test_three.py:14: AssertionError

-------------------- Captured stdout call -----------------------------------

Task(summary='sit there', owner='brain', done=False, id=None)

Task(summary='do something', owner='okken', done=False, id=None)

____________________ test_dict_equal ________________________________

    def test_dict_equal():

        t1_dict = Task('make sandwich', 'okken')._asdict()

        t2_dict = Task('make sandwich', 'okkem')._asdict()

        print(t1_dict)

        print(t2_dict)

>       assert t1_dict == t2_dict

E       AssertionError: assert OrderedDict([...('id', None)]) == OrderedDict([(...('id', None)])

E         Omitting 3 identical items, use -vv to show

E         Differing items:

E         {'owner': 'okken'} != {'owner': 'okkem'}

E         Full diff:

E         OrderedDict([('summary', 'make sandwich'),

E         -              ('owner', 'okken'),

E         ?                             ^...

E

E         ...Full output truncated (5 lines hidden), use '-vv' to show

test_three.py:22: AssertionError

--------------------------- Captured stdout call --------------------------------

OrderedDict([('summary', 'make sandwich'), ('owner', 'okken'), ('done', False), ('id', None)])

OrderedDict([('summary', 'make sandwich'), ('owner', 'okkem'), ('done', False), ('id', None)])

================= 2 failed in 0.13 seconds ============================

预期异常

"""

在Task项目的API中，有几个地方可能抛出异常

def add(task):  # type:(Task) ->int

def get(task_id):  # type:(int) ->Task

def list_tasks(owner=None):  # type:(str|None) ->list of task

def count():  # type:(None) ->int

def update(task_id, task):  # type:(int, Task) ->None

def delete(task_id):  # type:(int) ->None

def delete_all():  # type:() ->None

def unique_id():  # type:() ->int

def start_tasks_db(db_path, db_type):  # type:(str, str) ->None

def stop_tasks_db():  # type:() ->None

"""

import pytest

import tasks

def test_add_raises():

    with pytest.raises(TypeError):

        tasks.add(task='no a Task object')

"""

测试用例中有with pytest.raise(TypeError)生命，意味着无论with结构中的内容是什么

都至少会发生TypeError异常，如果测试通过，说明确实发生了我们预期TypeError，如果抛出的是其他类型的异常

则与我们预期的异常不一致，测试用例执行失败

"""

def test_start_tasks_db_raises():

    with pytest.raises(ValueError) as excinfo:

        tasks.start_tasks_db('some/great/path', 'mysql')

    exception_msg = excinfo.value.args[0]

    assert exception_msg == "db_type must be a 'tiny' or 'mongo' "

测试函数的标记

from collections import namedtuple

import pytest

Task = namedtuple('Task', ['summary','owner','done','id'])

# __new__.__defaults__创建默认的Task对象

Task.__new__.__defaults__ = (None, None, False, None)

@pytest.mark.smoke

def test_task_equality():

    t1 = Task('sit there', 'brain')

    t2 = Task('do something', 'okken')

    print(t1)

    print(t2)

    assert t1 == t2

@pytest.mark.dict

@pytest.mark.smoke

def test_dict_equal():

    t1_dict = Task('make sandwich', 'okken')._asdict()

    t2_dict = Task('make sandwich', 'okkem')._asdict()

    print(t1_dict)

    print(t2_dict)

    assert t1_dict == t2_dict

执行结果如下：

E:\Programs\Python\Python_Pytest\TestScripts>pytest -v -m 'smoke' test_five.py

================ test session starts =====================

platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 -- c:\python37\python.exe

cachedir: .pytest_cache

rootdir: E:\Programs\Python\Python_Pytest\TestScripts

plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3

collected 2 items                                                                                                                                                          

test_five.py::test_task_equality FAILED                                                                                                                              [ 50%]

test_five.py::test_dict_equal FAILED                                                                                                                                 [100%]

=================== FAILURES ==============================

______________ test_task_equality _________________________

    @pytest.mark.smoke

    def test_task_equality():

        t1 = Task('sit there', 'brain')

        t2 = Task('do something', 'okken')

        print(t1)

        print(t2)

>       assert t1 == t2

E       AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None)

E         At index 0 diff: 'sit there' != 'do something'

E         Full diff:

E         - Task(summary='sit there', owner='brain', done=False, id=None)

E         ?                ^^^  ^^^          ^^^^

E         + Task(summary='do something', owner='okken', done=False, id=None)

E         ?               +++ ^^^  ^^^          ^^^^

test_five.py:14: AssertionError

----------------------- Captured stdout call ----------------------------------

Task(summary='sit there', owner='brain', done=False, id=None)

Task(summary='do something', owner='okken', done=False, id=None)

___________________ test_dict_equal ___________________

    @pytest.mark.dict

    @pytest.mark.smoke

    def test_dict_equal():

        t1_dict = Task('make sandwich', 'okken')._asdict()

        t2_dict = Task('make sandwich', 'okkem')._asdict()

        print(t1_dict)

        print(t2_dict)

>       assert t1_dict == t2_dict

E       AssertionError: assert OrderedDict([...('id', None)]) == OrderedDict([(...('id', None)])

E         Omitting 3 identical items, use -vv to show

E         Differing items:

E         {'owner': 'okken'} != {'owner': 'okkem'}

E         Full diff:

E         OrderedDict([('summary', 'make sandwich'),

E         -              ('owner', 'okken'),

E         ?                             ^...

E

E         ...Full output truncated (5 lines hidden), use '-vv' to show

test_five.py:24: AssertionError

------------------------ Captured stdout call -------------------------------

OrderedDict([('summary', 'make sandwich'), ('owner', 'okken'), ('done', False), ('id', None)])

OrderedDict([('summary', 'make sandwich'), ('owner', 'okkem'), ('done', False), ('id', None)])

================ warnings summary =========================

c:\python37\lib\site-packages\_pytest\mark\structures.py:324

  c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.smoke - is this a typo?  You can register custom marks to avoi

d this warning - for details, see https://docs.pytest.org/en/latest/mark.html

    PytestUnknownMarkWarning,

c:\python37\lib\site-packages\_pytest\mark\structures.py:324

  c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.dict - is this a typo?  You can register custom marks to avoid

 this warning - for details, see https://docs.pytest.org/en/latest/mark.html

    PytestUnknownMarkWarning,

-- Docs: https://docs.pytest.org/en/latest/warnings.html

============== 2 failed, 2 warnings in 0.22 seconds =======================

在命令行执行使用了 -m marker_name参数，pytest在执行时会自动寻找被标记为marker_name的测试方法去执行，同时-m还支持and、or、not关键字，如下方式：

E:\Programs\Python\Python_Pytest\TestScripts>pytest -v -m "smoke and not dict" test_five.py

=========== test session starts ==============================

platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 -- c:\python37\python.exe

cachedir: .pytest_cache

rootdir: E:\Programs\Python\Python_Pytest\TestScripts

plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3

collected 2 items / 1 deselected / 1 selected                                                                                                                              

test_five.py::test_task_equality FAILED                                                                                                                              [100%]

=============== FAILURES ==================

_______________ test_task_equality ____________________________

    @pytest.mark.smoke

    def test_task_equality():

        t1 = Task('sit there', 'brain')

        t2 = Task('do something', 'okken')

        print(t1)

        print(t2)

>       assert t1 == t2

E       AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None)

E         At index 0 diff: 'sit there' != 'do something'

E         Full diff:

E         - Task(summary='sit there', owner='brain', done=False, id=None)

E         ?                ^^^  ^^^          ^^^^

E         + Task(summary='do something', owner='okken', done=False, id=None)

E         ?               +++ ^^^  ^^^          ^^^^

test_five.py:14: AssertionError

--------------- Captured stdout call ------------------------------

Task(summary='sit there', owner='brain', done=False, id=None)

Task(summary='do something', owner='okken', done=False, id=None)

================ warnings summary ====================

c:\python37\lib\site-packages\_pytest\mark\structures.py:324

  c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.smoke - is this a typo?  You can register custom marks to avoi

d this warning - for details, see https://docs.pytest.org/en/latest/mark.html

    PytestUnknownMarkWarning,

c:\python37\lib\site-packages\_pytest\mark\structures.py:324

  c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.dict - is this a typo?  You can register custom marks to avoid

 this warning - for details, see https://docs.pytest.org/en/latest/mark.html

    PytestUnknownMarkWarning,

-- Docs: https://docs.pytest.org/en/latest/warnings.html

============= 1 failed, 1 deselected, 2 warnings in 0.14 seconds ===========

跳过测试

from collections import namedtuple

import pytest

Task = namedtuple('Task', ['summary','owner','done','id'])

# __new__.__defaults__创建默认的Task对象

Task.__new__.__defaults__ = (None, None, False, None)

@pytest.mark.smoke

def test_task_equality():

    t1 = Task('sit there', 'brain')

    t2 = Task('do something', 'okken')

    print(t1)

    print(t2)

    assert t1 == t2

@pytest.mark.dict

@pytest.mark.smoke

@pytest.mark.skip(reason="跳过原因你不知道吗？")

def test_dict_equal():

    t1_dict = Task('make sandwich', 'okken')._asdict()

    t2_dict = Task('make sandwich', 'okkem')._asdict()

    print(t1_dict)

    print(t2_dict)

    assert t1_dict == t2_dict

执行结果：

E:\Programs\Python\Python_Pytest\TestScripts>pytest -v test_five.py

=============== test session starts ===================================

platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0 -- c:\python37\python.exe

cachedir: .pytest_cache

rootdir: E:\Programs\Python\Python_Pytest\TestScripts

plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3

collected 2 items                                                                                                                                                          

test_five.py::test_task_equality FAILED                                                                                                                              [ 50%]

test_five.py::test_dict_equal SKIPPED                                                                                                                                [100%]

============== FAILURES ==================================

__________________ test_task_equality _______________________________

    @pytest.mark.smoke

    def test_task_equality():

        t1 = Task('sit there', 'brain')

        t2 = Task('do something', 'okken')

        print(t1)

        print(t2)

>       assert t1 == t2

E       AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None)

E         At index 0 diff: 'sit there' != 'do something'

E         Full diff:

E         - Task(summary='sit there', owner='brain', done=False, id=None)

E         ?                ^^^  ^^^          ^^^^

E         + Task(summary='do something', owner='okken', done=False, id=None)

E         ?               +++ ^^^  ^^^          ^^^^

test_five.py:14: AssertionError

------------------ Captured stdout call --------------------------------

Task(summary='sit there', owner='brain', done=False, id=None)

Task(summary='do something', owner='okken', done=False, id=None)

=========== warnings summary ==============================

c:\python37\lib\site-packages\_pytest\mark\structures.py:324

  c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.smoke - is this a typo?  You can register custom marks to avoi

d this warning - for details, see https://docs.pytest.org/en/latest/mark.html

    PytestUnknownMarkWarning,

c:\python37\lib\site-packages\_pytest\mark\structures.py:324

  c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.dict - is this a typo?  You can register custom marks to avoid

 this warning - for details, see https://docs.pytest.org/en/latest/mark.html

    PytestUnknownMarkWarning,

-- Docs: https://docs.pytest.org/en/latest/warnings.html

=========== 1 failed, 1 skipped, 2 warnings in 0.21 seconds ================

从测试结果中我们看到，测试用例test_five.py::test_dict_equal SKIPPED 被跳过了，然而跳过原因并没有如期的展示出来，可以使用参数-rs来展示跳过原因，如下方式：

E:\Programs\Python\Python_Pytest\TestScripts>pytest -rs test_five.py

===================== test session starts ===========================

platform win32 -- Python 3.7.3, pytest-4.5.0, py-1.8.0, pluggy-0.11.0

rootdir: E:\Programs\Python\Python_Pytest\TestScripts

plugins: xdist-1.29.0, timeout-1.3.3, repeat-0.8.0, instafail-0.4.1, forked-1.0.2, emoji-0.2.0, allure-pytest-2.6.3

collected 2 items                                                                                                                                                          

test_five.py Fs                                                                                                                                                      [100%]

============ FAILURES ====================================

__________________________ test_task_equality _______________________

    @pytest.mark.smoke

    def test_task_equality():

        t1 = Task('sit there', 'brain')

        t2 = Task('do something', 'okken')

        print(t1)

        print(t2)

>       assert t1 == t2

E       AssertionError: assert Task(summary=...alse, id=None) == Task(summary='...alse, id=None)

E         At index 0 diff: 'sit there' != 'do something'

E         Use -v to get the full diff

test_five.py:14: AssertionError

-------------------- Captured stdout call ----------------------------------

Task(summary='sit there', owner='brain', done=False, id=None)

Task(summary='do something', owner='okken', done=False, id=None)

========== warnings summary ====================

c:\python37\lib\site-packages\_pytest\mark\structures.py:324

  c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.smoke - is this a typo?  You can register custom marks to avoi

d this warning - for details, see https://docs.pytest.org/en/latest/mark.html

    PytestUnknownMarkWarning,

c:\python37\lib\site-packages\_pytest\mark\structures.py:324

  c:\python37\lib\site-packages\_pytest\mark\structures.py:324: PytestUnknownMarkWarning: Unknown pytest.mark.dict - is this a typo?  You can register custom marks to avoid

 this warning - for details, see https://docs.pytest.org/en/latest/mark.html

    PytestUnknownMarkWarning,

-- Docs: https://docs.pytest.org/en/latest/warnings.html

============ short test summary info ====================

SKIPPED [1] test_five.py:17: 跳过原因你不知道吗？

========== 1 failed, 1 skipped, 2 warnings in 0.14 seconds =================

还可以给跳过添加理由，例如当selenium版本是1.0.4的时候跳过

from collections import namedtuple

import pytest

import selenium

Task = namedtuple('Task', ['summary','owner','done','id'])

# __new__.__defaults__创建默认的Task对象

Task.__new__.__defaults__ = (None, None, False, None)

@pytest.mark.smoke

def test_task_equality():

    t1 = Task('sit there', 'brain')

    t2 = Task('do something', 'okken')

    print(t1)

    print(t2)

    assert t1 == t2

@pytest.mark.dict

@pytest.mark.smoke

@pytest.mark.skipif(selenium.__version__ == '1.0.4', reason="跳过原因你不知道吗？")

def test_dict_equal():

    t1_dict = Task('make sandwich', 'okken')._asdict()

    t2_dict = Task('make sandwich', 'okkem')._asdict()

    print(t1_dict)

    print(t2_dict)

    assert t1_dict == t2_dict

运行测试子集

运行单个目录，只需要将目录作为pytest的参数即可

pytest -v test/func  --tb=no

1

运行单个测试函数，只需要在文件名后添加::符号和函数名

pytest -v test/func/test_five.py::test_dict_equal

1

运行单个测试类，与运行单个测试函数类似,在文件名后添加::符号和类名

pytest -v test/func/test_five.py::Test_Update

1

运行单个测试类中的测试方法，在文件名后添加::符号和类名然后再跟::符号和函数名

pytest -v test/func/test_five.py::Test_Update::test_dict_equal


















												


																

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