Pytest----快速入门

一、Pytest的安装

(1) 安装

pip install pytest

(2)查看版本，如下表示安装OK

$ pytest --version
pytest 6.2.5

(3)升级

pip install -U pytest

二、创建第一个测试脚本

(1)四行代码即可写一个测试脚本，如下，文件命名为 test_sample.py

def func(x):
    return x + 1

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

(2)打开cmd窗口或者从pycharm进入终端，或者使用git shell，进入到test_sample.py文件所在的目录，然后执行pytest命令即开始执行脚本

$ pytest
=========================== test session starts ============================
platform linux -- Python 3.x.y, pytest-6.x.y, py-1.x.y, pluggy-1.x.y
cachedir: $PYTHON_PREFIX/.pytest_cache
rootdir: $REGENDOC_TMPDIR
collected 1 item

test_sample.py F                                                     [100%]

================================= FAILURES =================================
_______________________________ test_answer ________________________________

    def test_answer():
>       assert func(3) == 5
E       assert 4 == 5
E        +  where 4 = func(3)

test_sample.py:6: AssertionError
========================= short test summary info ==========================
FAILED test_sample.py::test_answer - assert 4 == 5
============================ 1 failed in 0.12s =============================

三、使用类组织测试函数

(1)使用类组织测试函数，注意不能写__init__()函数，创建test_class.py文件，代码如下：

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

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

然后执行pytest test_class.py

$ pytest test_class.py
============================= test session starts =============================
platform win32 -- Python 3.9.6, pytest-6.2.5, py-1.10.0, pluggy-1.0.0 -- D:\python39\python.exe
cachedir: .pytest_cache
hypothesis profile 'default' -> database=DirectoryBasedExampleDatabase('G:\\src\\blog\\tests\\demo\\.hypothesis\\examples')
rootdir: G:\src\blog\tests, configfile: pytest.ini
plugins: allure-pytest-2.9.43, caterpillar-pytest-0.0.2, hypothesis-6.31.6, forked-1.3.0, rerunfailures-10.1, xdist-2.3.0
collecting ... collected 2 items

test_class.py::TestClass::test_one PASSED
test_class.py::TestClass::test_two FAILED

================================== FAILURES ===================================
_____________________________ TestClass.test_two ______________________________

self = <test_class.TestClass object at 0x000001BC163991F0>

    def test_two(self):
        x = "hello"
>       assert hasattr(x, "check")
E       AssertionError: assert False
E        +  where False = hasattr('hello', 'check')

test_class.py:8: AssertionError
=========================== short test summary info ===========================
FAILED test_class.py::TestClass::test_two - AssertionError: assert False
========================= 1 failed, 1 passed in 0.35s =========================

(2)使用类组织测试函数的好处

• 可以有效的组织用例
• 可以仅在类中共享fixture
• 可以在类上打标签从而对类中的所有用例打标签

(3)使用类组织测试函数时需要特别注意，勒种的每个用例都是测试类的一个独立的对象，类中的用例如果通过类属性共享变量将是非常糟糕的设计，如下：

# content of test_class_demo.py
class TestClassDemoInstance:
    value = 0

    def test_one(self):
        self.value = 1
        assert self.value == 1

    def test_two(self):
        assert self.value == 1

执行结果如下：

$ pytest -k TestClassDemoInstance -q
.F                                                                   [100%]
================================= FAILURES =================================
______________________ TestClassDemoInstance.test_two ______________________

self = <test_class_demo.TestClassDemoInstance object at 0xdeadbeef0002>

    def test_two(self):
>       assert self.value == 1
E       assert 0 == 1
E        +  where 0 = <test_class_demo.TestClassDemoInstance object at 0xdeadbeef0002>.value

test_class_demo.py:9: AssertionError
========================= short test summary info ==========================
FAILED test_class_demo.py::TestClassDemoInstance::test_two - assert 0 == 1
1 failed, 1 passed in 0.12s