如何为带some_marker标记的pytest测试自动添加some_fixture

你当前的实现需要手动在测试函数参数中指定some_fixture，可以通过以下两种方式实现自动绑定，无需手动传入fixture参数：

方法一：利用autouse自动触发fixture #

修改conftest.py中的some_fixture，设置autouse=True，并在fixture内部判断当前测试是否带有目标标记，仅当存在标记时执行上下文操作：

# conftest.py

class ContextManager:
    def __init__(self, some_args):
        self.some_args = some_args

    def __enter__(self):
        # 执行测试前的操作
        pass

    def __exit__(self, exc_type, exc_val, exc_tb):
        # 执行测试后的操作
        pass


@pytest.fixture(autouse=True)
def some_fixture(request):
    marker = request.node.get_closest_marker("some_marker")
    if not marker:
        yield
        return
    
    some_args = marker.kwargs.get("some_args")
    with ContextManager(some_args):
        yield


def pytest_configure(config):
    config.addinivalue_line("markers", "some_marker(some_args): 标记需要执行特定前后操作的测试")

修改后，测试代码无需手动传入some_fixture参数，只要标记了@pytest.mark.some_marker就会自动触发fixture逻辑：

# module_test.py
import pytest

@pytest.mark.some_marker(some_args=[...])
def test_function():
    # 测试逻辑
    pass

方法二：通过钩子函数修改测试依赖 #

如果不想让fixture全局自动触发，可使用pytest_collection_modifyitems钩子，在测试收集阶段为带标记的测试自动添加fixture依赖：

# conftest.py

class ContextManager:
    def __init__(self, some_args):
        self.some_args = some_args

    def __enter__(self):
        # 执行测试前的操作
        pass

    def __exit__(self, exc_type, exc_val, exc_tb):
        # 执行测试后的操作
        pass


@pytest.fixture
def some_fixture(request):
    some_args = request.node.get_closest_marker("some_marker").kwargs.get("some_args")
    with ContextManager(some_args):
        yield


def pytest_configure(config):
    config.addinivalue_line("markers", "some_marker(some_args): 标记需要执行特定前后操作的测试")

def pytest_collection_modifyitems(items):
    for item in items:
        if item.get_closest_marker("some_marker"):
            # 为测试添加some_fixture依赖
            item.fixturenames.append("some_fixture")

测试代码同样无需手动传入fixture参数：

# module_test.py
import pytest

@pytest.mark.some_marker(some_args=[...])
def test_function():
    # 测试逻辑
    pass

内容的提问来源于stack exchange，提问作者Kirill Lekhov