[Pytest] Pytest 测试框架 --- 基础知识

What is a Test Framework?

A testing framework is a set of guidelines or rules used for creating and designing test cases.
A framework is comprised of a combination of practices and tools that are designed to help QA professionals test more efficiently.

Benefits of a Test Automation Framework

Utilizing a framework for automated testing will increase a team’s test speed and efficiency, improve test accuracy, and will reduce test maintenance costs as well as lower risks. They are essential to an efficient automated testing process for a few key reasons:
Improved test efficiency
Lower maintenance costs
Minimal manual intervention
Maximum test coverage
Reusability of code

Pytest

The pytest framework makes it easy to write small, readable tests, and can scale to support complex functional testing for applications and libraries.

pytest requires: Python 3.7+ or PyPy3. 1
Run the following command in your command line:
pip install -U pytest
Check that you installed the correct version:
pytest --version pytest 7.1.2

Pytest parameter

Pytest parameter:

参数：-s（用于显示测试用例中的 print()信息）
参数：-v（用于详细显示测试用例的执行过程）
参数：-q（简化控制台输出，只显示整体测试结果）
参数：-x（运行到失败的用例就停止）
参数：--maxfail=x（出现 x 个失败用例既停止）
参数：--collect-only（收集将要执行的用例，但不会执行用例）
参数： -m （只运行带有对应标识的测试用例，
需使用@pytest.mark.xxxx进行修饰，后面跟自己的标识，一般进行标记冒烟测试，系统测试，登录测试等）�参数：--result-log=path（将执行结果保存到指定路径下）
参数：--durations=num （显示执行最慢的测试用例，一般用于调优，注意如果要显示执行时间为 0 秒的用例时，要加上参数-vv）

运行失败后该用例重新运行最多3次

参数： --reruns 3

Run multiple tests

pytest will run all files of the form test_*.py or *_test.py in the current directory and its subdirectories.
More generally, it follows standard test discovery rules.

Grouping tests in classes can be beneficial for the following reasons:
• Test organization
• Sharing fixtures for tests only in that particular class
• Applying marks at the class level and having them implicitly apply to all tests

Fixture

_Scope = Literal["session", "package", "module", "class", "function"]

image.png

Fixture scopes

Fixtures are created when first requested by a test, and are destroyed based on their scope:
• function: the default scope, the fixture is destroyed at the end of the test.
• class: the fixture is destroyed during teardown of the last test in the class.
• module: the fixture is destroyed during teardown of the last test in the module.
• package: the fixture is destroyed during teardown of the last test in the package.
• session: the fixture is destroyed at the end of the test session

Params

Fixture functions can be parametrized in which case they will be called multiple times, each time executing the set of dependent tests,

Using marks with parametrized fixtures

pytest.param() can be used to apply marks in values sets of parametrized fixtures in the same way that they can be
used with @pytest.mark.parametrize.

How to mark test functions with attributes

Here are some of the builtin markers:
• usefixtures - use fixtures on a test function or class
• filterwarnings - filter certain warnings of a test function
• skip - always skip a test function
• skipif - skip a test function if a certain condition is met
• xfail - produce an “expected failure” outcome if a certain condition is met
• parametrize - perform multiple calls to the same test function.

conftest.py

conftest.py配置需要注意以下点：
conftest.py配置脚本名称是固定的，不能改名称
conftest.py与运行的用例要在同一个pakage下，并且有init.py文件
不需要import导入 conftest.py，pytest用例会自动查找

How to write and report assertions in tests

Asserting with the assert statement
pytest allows you to use the standard Python assert for verifying expectations and values in Python tests. For
example, you can write the following:

content of test_assert1.py

def f():
    ret =  3 % 2
    return ret

def test_function():
assert f() == 0

pytest has support for showing the values of the most common subexpressions including calls, attributes, comparisons, and binary and unary operators.

assert f() % 2 == 0, "value was odd, should be even"

Assertions about expected exceptions
In order to write assertions about raised exceptions, you can use pytest.raises() as a context manager like this: