如何为pytest同时配置session与class级别的setup/teardown？

问题核心 #

你的Session级fixture未执行，原因是Pytest的fixture仅在被显式引用时才会触发，同时代码中存在几处语法错误，导致功能异常：

1. test_suite_2.py中@pytest.fixtures多了一个s，正确应为@pytest.fixture
2. @pytest.mark.usefixture应为复数形式@pytest.mark.usefixtures，才能同时指定多个fixture
3. 测试类中的测试方法未接收self参数，不符合类方法定义规范

解决方案 #

方法1：在测试类中显式引用Session级Fixture #

修改测试文件，在usefixtures中同时指定类级和Session级fixture，同时修正语法错误：

修正后的test_suite_1.py

import logging
import pytest
from common_setup import set_session_data

@pytest.fixture(scope="class")
def set_data():
    # Setup
    logging.info("In test suite 1 setup")
    # Teardown
    yield
    logging.info("In test suite 1 teardown")

@pytest.mark.usefixtures("set_data", "set_session_data")
class TestClass:
    def test_case_1(self):
        logging.info("In test suite 1, test case 1")

    def test_case_2(self):
        logging.info("In test suite 1, test case 2")

修正后的test_suite_2.py

import logging
import pytest
from common_setup import set_session_data

@pytest.fixture(scope="class")
def set_data():
    # Setup
    logging.info("In test suite 2 setup")
    # Teardown
    yield
    logging.info("In test suite 2 teardown")

@pytest.mark.usefixtures("set_data", "set_session_data")
class TestClass:
    def test_case_1(self):
        logging.info("In test suite 2, test case 1")

    def test_case_2(self):
        logging.info("In test suite 2, test case 2")

方法2：使用conftest.py自动加载Session级Fixture #

如果不想在每个测试文件中手动导入Session fixture，可以将common_setup.py的内容迁移到conftest.py（Pytest会自动识别该文件中的fixture，无需导入）：

新建conftest.py

import logging
import pytest

@pytest.fixture(scope="session")
def set_session_data():
    logging.info("In session setup")
    yield
    logging.info("In session teardown")

此时测试文件无需再导入common_setup，直接在usefixtures中指定set_session_data即可，比如test_suite_1.py可简化为：

import logging
import pytest

@pytest.fixture(scope="class")
def set_data():
    logging.info("In test suite 1 setup")
    yield
    logging.info("In test suite 1 teardown")

@pytest.mark.usefixtures("set_data", "set_session_data")
class TestClass:
    def test_case_1(self):
        logging.info("In test suite 1, test case 1")

    def test_case_2(self):
        logging.info("In test suite 1, test case 2")

验证执行结果 #

运行测试后，日志将符合预期顺序：

2022-11-28 15:16:25 INFO In session setup
2022-11-28 15:16:25 INFO In test suite 1 setup
2022-11-28 15:16:25 INFO In test suite 1, test case 1
2022-11-28 15:16:25 INFO In test suite 1, test case 2
2022-11-28 15:16:25 INFO In test suite 1 teardown
2022-11-28 15:16:25 INFO In test suite 2 setup
2022-11-28 15:16:25 INFO In test suite 2, test case 1
2022-11-28 15:16:25 INFO In test suite 2, test case 2
2022-11-28 15:16:25 INFO In test suite 2 teardown
2022-11-28 15:16:25 INFO In session teardown

额外说明 #

• Session级fixture的scope="session"确保它在整个测试会话中仅执行一次（启动时setup，所有测试完成后teardown）
• 类级fixture的scope="class"确保每个测试类执行一次setup和teardown
• 如果希望Session fixture自动生效（无需在每个类中指定），可以在conftest.py中使用@pytest.fixture(scope="session", autouse=True)，Pytest会自动触发该fixture

内容的提问来源于stack exchange，提问作者NevNein