可以查看所有收集的測試的 session-fixture

session 作用域的 fixture 實際上可以存取所有收集的測試項目。以下是一個 fixture 函數的範例，它遍歷所有收集的測試，並查看它們的測試類別是否定義了 callme 方法並調用它

# content of conftest.py

import pytest


@pytest.fixture(scope="session", autouse=True)
def callattr_ahead_of_alltests(request):
    print("callattr_ahead_of_alltests called")
    seen = {None}
    session = request.node
    for item in session.items:
        cls = item.getparent(pytest.Class)
        if cls not in seen:
            if hasattr(cls.obj, "callme"):
                cls.obj.callme()
            seen.add(cls)

現在測試類別可以定義一個 callme 方法，該方法將在運行任何測試之前被調用

# content of test_module.py


class TestHello:
    @classmethod
    def callme(cls):
        print("callme called!")

    def test_method1(self):
        print("test_method1 called")

    def test_method2(self):
        print("test_method2 called")


class TestOther:
    @classmethod
    def callme(cls):
        print("callme other called")

    def test_other(self):
        print("test other")


# works with unittest as well ...
import unittest


class SomeTest(unittest.TestCase):
    @classmethod
    def callme(self):
        print("SomeTest callme called")

    def test_unit1(self):
        print("test_unit1 method called")

如果你在沒有輸出捕獲的情況下運行這個

$ pytest -q -s test_module.py
callattr_ahead_of_alltests called
callme called!
callme other called
SomeTest callme called
test_method1 called
.test_method2 called
.test other
.test_unit1 method called
.
4 passed in 0.12s