Pytest学习笔记

记录下pytest官方文档的阅读笔记，以便后续参考使用。非完整版，个人理解为主，难免有误，望理解。

安装与快速使用

安装

$ pip install pytest
$ pytest --version

第一个test

01\test_sample.py

def func(x):
    return x + 1


def test_answer():
    assert  func(3) == 5

运行

# 默认会执行当前目录及子目录的所有test_*.py或*_test.py文件。用例执行成功为.，失败为F
$ pytest

# 静默执行
$ pytest -q 01\test_sample.py

# 调试方式执行，可以打印print日志等详情信息
$ pytest 01\test_sample.py -s -v

# python模块方式执行
$ python -m pytest 01\test_sample.py

# 执行单个目录下的tests
$ python 01\

test类包含多个tests

01\test_class.py

# pytest默认会执行所有test_前缀的函数
class TestClass(object):

    def test_one(self):
        x = "this"
        assert 'h' in x

    def test_two(self):
        x = 'hello'
        assert hasattr(x, 'check')

pytest常见的exit codes

Exit code 0 所有tests全部通过

Exit code 1 部分tests失败了

Exit code 2 用户中止test执行

Exit code 3 执行test时，内部报错

Exit code 4 pytest命令使用姿势不对

Exit code 5 无tests可执行

pytest常见帮助选项

$ pytest --version      # 显示版本信息
$ pytest --fixtures     # 显示内置可用的函数参数
$ pytest -h | --help    # 显示帮助信息
$ pytest -x             # 第一个失败时即停止
$ pytest --maxfail=2    # 两个失败后即停止

pytest fixtures(明确的、模块化的、可扩展的)

1. fixtures由明确的命名，可以通过测试函数、模块、类或整个项目激活
2. fixtures以模块化的方式实现，因为每个名称会触发一个fixtures函数，同时函数本身也可以使用其它fixtures
3. fixtures管理从简单的单元到复杂的功能测试，允许参数化fixtures和根据配置和组件进行测试或通过函数、类、模块或整个test会话范围重用fixtures

Fixtures作为函数参数

测试函数可以接收fixture对象作为输入参数，使用@pytest.fixture

test_smtpsimple.py

import pytest


@pytest.fixture
def smtp_connection():
    import smtplib
    return smtplib.SMTP(host='smtp.qq.com',port=587, timeout=5)


def test_ehlo(smtp_connection):
    response, msg = smtp_connection.ehlo()
    assert response == 250
    assert 0

$ pytest 01\test_smtpsimple.py
============================= test session starts =============================
platform win32 -- Python 3.6.4, pytest-3.7.4, py-1.6.0, pluggy-0.7.1
rootdir: D:\projects\python\pytest_notes, inifile:
collected 1 item                                                               

01\test_smtpsimple.py F                                                  [100%]

================================== FAILURES ===================================
__________________________________ test_ehlo __________________________________

smtp_connection = <smtplib.SMTP object at 0x0000021F3E041828>

    def test_ehlo(smtp_connection):
        response, msg = smtp_connection.ehlo()
        assert response == 250
>       assert 0
E       assert 0

01\test_smtpsimple.py:13: AssertionError
========================== 1 failed in 1.45 seconds ===========================

# 测试函数调用smtp_connection参数，而smptlib.SMTP实列由fixture函数创建

Fixtures 依赖注入

Fixtures 允许测试函数非常容易的接收和使用特定的预初始化程序对象，而无需特别去关注import/setup/cleanup等细节

config.py：共享fixture函数

如果多个测试文件需要用到一个fixture函数，则把它写到conftest.py文件当中。使用时无需导入这个fixture函数，因为pytest会自动获取

共享测试数据

1. 如果在测试中，需要从文件加载测试数据到tests，可以使用fixture方式加载，pytest有自动缓存机制
2. 另外一种方式是添加测试数据文件到tests目录，如使用pytest-datadir和pytest-datafiles插件

Scope：共享一个fixture实列（类、模块或会话）

Scope - module

conftest.py

import pytest
import smtplib


@pytest.fixture(scope='module')
def smtp_connection():
    return smtplib.SMTP(host='smtp.qq.com', port=587, timeout=5)

test_module.py

def test_ehlo(smtp_connection):
    response, msg = smtp_connection.ehlo()
    assert response == 250
    assert b'smtp.qq.com' in msg
    assert 0


def test_noop(smtp_connection):
    response, msg = smtp_connection.noop()
    assert response == 250
    assert 0

执行

$ pytest 01\test_module.py
============================= test session starts =============================
platform win32 -- Python 3.6.4, pytest-3.7.4, py-1.6.0, pluggy-0.7.1
rootdir: D:\projects\python\pytest_notes, inifile:
collected 2 items                                                              

01\test_module.py FF                                                     [100%]

================================== FAILURES ===================================
__________________________________ test_ehlo __________________________________

smtp_connection = <smtplib.SMTP object at 0x0000018E14F13780>   # 1

    def test_ehlo(smtp_connection):
        response, msg = smtp_connection.ehlo()
        assert response == 250
        assert b'smtp.qq.com' in msg
>       assert 0
E       assert 0

01\test_module.py:7: AssertionError
__________________________________ test_noop __________________________________

smtp_connection = <smtplib.SMTP object at 0x0000018E14F13780>   # 2 可以看到1和2的实列对象为同一个

    def test_noop(smtp_connection):
        response, msg = smtp_connection.noop()
>       assert response == 250
E       assert 530 == 250

01\test_module.py:12: AssertionError
========================== 2 failed in 1.42 seconds ===========================

Scope - session

import pytest
import smtplib


# 所有tests能使用到它的，都是共享同一个fixture值
@pytest.fixture(scope='session')
def smtp_connection():
    return smtplib.SMTP(host='smtp.qq.com', port=587, timeout=5)

Scope - class

import pytest
import smtplib


# 每个test类，都是共享同一个fixture值
@pytest.fixture(scope='class')
def smtp_connection():
    return smtplib.SMTP(host='smtp.qq.com', port=587, timeout=5)

高级别的scope fixtures第一个实例化

@pytest.fixture(scope="session")
def s1():
    pass

@pytest.fixture(scope="module")
def m1():
    pass

@pytest.fixture
def f1(tmpdir):
    pass

@pytest.fixture
def f2():
    pass

def test_foo(f1, m1, f2, s1):
...

1. s1： 是最高级别的fxiture（session）
2. m1： 是第二高级别的fixture（module）
3. tmpdir： 是一个function的fixture，依赖f1
4. f1：在test_foo列表参数当中，是第一个function的fixture
5. f2：在test_foo列表参数当中，是最后一个function的fixture

Fixture结束或执行teardown代码

1. 当fixture超过其scope范围，pytest支持执行fixture特定的结束代码
2. 使用yield替换return，所有yield声明之后的代码都作为teardown代码处理

yield替换return

conftest.py

import pytest
import smtplib


# print和smtp_connection.close()只会在module范围内最后一个test执行结束后执行，除非中间有异常
@pytest.fixture(scope='module')
def smtp_connection():
    smtp_connection = smtplib.SMTP(host='smtp.qq.com', port=587, timeout=5)
    yield smtp_connection
    print('teardown smtp')  
    smtp_connection.close()

执行

$ pytest -s -q 01\test_module.py --tb=no
FFteardown smtp

2 failed in 0.96 seconds

with替换yield

conftest.py

import pytest
import smtplib


# 使用了with声明，smtp_connection等test执行完后，自动关闭
# 注意：yield之前的setup代码发生了异常，teardown代码将不会被调用
@pytest.fixture(scope='module')
def smtp_connection():
    with smtplib.SMTP(host='smtp.qq.com', port=587, timeout=5) as smtp_connection:
        yield smtp_connection

使用addfinalizer清理

yield和addfinalizer方法类似，但addfinalizer有两个不同的地方

1. 可以注册多个finalizer函数

2. 不论setup代码是否发生异常，均会关闭所有资源

   @pytest.fixture
   def equipments(request):
      r = []
      for port in ('C1', 'C3', 'C28'):
          equip = connect(port)
          request.addfinalizer(equip.disconnect)
          r.append(equip)
      return r
   # 假设C28抛出一次，C1和C2将正常被关闭。当然异常发生在finalize函数注册之前，它将不被执行
   

conftest.py

import pytest
import smtplib


@pytest.fixture(scope='module')
def smtp_connection(request):
    smtp_connection = smtplib.SMTP(host='smtp.qq.com', port=587, timeout=5)

    def fin():
        print('teardown smtp_connection')
        smtp_connection.close()
    request.addfinalizer(fin)
    return smtp_connection

执行

$ pytest -s -q 01\test_module.py --tb=no
FFteardown smtp_connection

2 failed in 0.99 seconds

Fixture可以使用request对象来管理 测试内容

Fixture函数可以接收一个request对象

conftest.py

import pytest
import smtplib


# 所有使用fixture的test module，都可以读取一个可选的smtpserver地址
@pytest.fixture(scope='module')
def smtp_connection(request):
    server = getattr(request.module, 'smtpserver', 'smtp.qq.com')
    smtp_connection = smtplib.SMTP(host=server, port=587, timeout=5)

    yield smtp_connection
    print('finalizing %s (%s)' % (smtp_connection, server))
    smtp_connection.close()

执行1

$ pytest -s -q --tb=no
.FFFfinalizing <smtplib.SMTP object at 0x00000266A3912470> (smtp.qq.com)
FF
5 failed, 1 passed in 2.11 seconds

test_anothersmtp.py

smtpserver = 'mail.python.org'  # 自动读取并替换fixture默认的值


def test_showhelo(smtp_connection):
    assert 0, smtp_connection.helo()

执行2

$ pytest -qq --tb=short 01\test_anothersmtp.py
F                                                                        [100%]
================================== FAILURES ===================================
________________________________ test_showhelo ________________________________
01\test_anothersmtp.py:5: in test_showhelo
    assert 0, smtp_connection.helo()
E   AssertionError: (250, b'mail.python.org')
E   assert 0
-------------------------- Captured stdout teardown ---------------------------
finalizing <smtplib.SMTP object at 0x000001C1F631DBE0> (mail.python.org)

Fixture工厂模式

在单个test中，fixture结果需要被多次使用

@pytest.fixture
def make_customer_record():
    def _make_customer_record(name):
        return {
            "name": name,
            "orders": []
        }
    return _make_customer_record

def test_customer_records(make_customer_record):
    customer_1 = make_customer_record("Lisa")
    customer_2 = make_customer_record("Mike")
    customer_3 = make_customer_record("Meredith")

# 创建的数据需要工厂管理时，采用这种方式
@pytest.fixture
def make_customer_record():
    created_records = []
    
    def _make_customer_record(name):
        record = models.Customer(name=name, orders=[])
        created_records.append(record)
        return record
    
    yield _make_customer_record

    for record in created_records:
        record.destroy()
        
def test_customer_records(make_customer_record):
    customer_1 = make_customer_record("Lisa")
    customer_2 = make_customer_record("Mike")
    customer_3 = make_customer_record("Meredith")

Fixture 参数

Fixture可以参数化，当需要执行多次时

conftest.py

import pytest
import smtplib


@pytest.fixture(scope='module',
                params=['smtp.qq.com', 'mail.python.org'])
def smtp_connection(request):
    smtp_connection = smtplib.SMTP(host=request.param, port=587, timeout=5)

    yield smtp_connection
    print('finalizing %s' % (smtp_connection))
    smtp_connection.close()

执行

$ pytest -q  01\test_module.py
FFFF                                                                     [100%]
================================== FAILURES ===================================
___________________________ test_ehlo[smtp.qq.com] ____________________________

smtp_connection = <smtplib.SMTP object at 0x000002769B09A908>

    def test_ehlo(smtp_connection):
        response, msg = smtp_connection.ehlo()
        assert response == 250
        assert b'smtp.qq.com' in msg
>       assert 0
E       assert 0

01\test_module.py:7: AssertionError
___________________________ test_noop[smtp.qq.com] ____________________________

smtp_connection = <smtplib.SMTP object at 0x000002769B09A908>

    def test_noop(smtp_connection):
        response, msg = smtp_connection.noop()
>       assert response == 250
E       assert 530 == 250

01\test_module.py:12: AssertionError
_________________________ test_ehlo[mail.python.org] __________________________

smtp_connection = <smtplib.SMTP object at 0x000002769B09AA58>

    def test_ehlo(smtp_connection):
        response, msg = smtp_connection.ehlo()
        assert response == 250
>       assert b'smtp.qq.com' in msg
E       AssertionError: assert b'smtp.qq.com' in b'mail.python.org\nPIPELINING\nSIZE 51200000\nETRN\nSTARTTLS\nAUTH DIGEST-MD5 NTLM CRAM-MD5\nENHANCEDST
ATUSCODES\n8BITMIME\nDSN\nSMTPUTF8'

01\test_module.py:6: AssertionError
---------------------------- Captured stdout setup ----------------------------
finalizing <smtplib.SMTP object at 0x000002769B09A908>
_________________________ test_noop[mail.python.org] __________________________

smtp_connection = <smtplib.SMTP object at 0x000002769B09AA58>

    def test_noop(smtp_connection):
        response, msg = smtp_connection.noop()
        assert response == 250
>       assert 0
E       assert 0

01\test_module.py:13: AssertionError
-------------------------- Captured stdout teardown ---------------------------
finalizing <smtplib.SMTP object at 0x000002769B09AA58>
4 failed in 4.29 seconds

标记fixture参数

test_fixture_marks.py

import pytest


@pytest.fixture(params=[0, 1, pytest.param(2, marks=pytest.mark.skip)])
def data_set(request):
    return request.param


def test_data(data_set):
    pass

执行

$ pytest 01\test_fixture_marks.py -v
============================= test session starts =============================
platform win32 -- Python 3.6.4, pytest-3.7.4, py-1.6.0, pluggy-0.7.1 -- d:\projects\python\pytest_notes\.venv\scripts\python.exe
cachedir: .pytest_cache
rootdir: D:\projects\python\pytest_notes, inifile:
collected 3 items                                                              

01/test_fixture_marks.py::test_data[0] PASSED                            [ 33%]
01/test_fixture_marks.py::test_data[1] PASSED                            [ 66%]
01/test_fixture_marks.py::test_data[2] SKIPPED                           [100%]

===================== 2 passed, 1 skipped in 0.14 seconds =====================

经典的xunit风格setup

Module级别的setup/teardown

如果有多个test函数或test类在一个模块内，可以选择的实现setup_module和teardown_module，一般模块内的所有函数都会调用一次

def setup_module(module):
    pass

def teardown_module(module):
    pass

Class级别的setup/teardown

在类内，所有的方法均会调用到

@classmethod
def setup_class(cls):
    pass

@classmethod
def teardown_class(cls):
    pass

Method和Function级别的setup/teardown

# 指定方法调用
def setup_method(self, method):
    pass

def teardown_method(self, method):
    pass

# 模块级别内可以直接使用function调用
def setup_function(function):
    pass

def teardown_function(function):
    pass