conftest.py

from __future__ import print_function

import pytest

@pytest.hookimpl(hookwrapper=True)
def pytest_fixture_setup(fixturedef, request):
    print("pytest_fixture_setup before", fixturedef, request)
    yield
    print("pytest_fixture_setup after", fixturedef, request)


@pytest.hookimpl(hookwrapper=True)
def pytest_runtest_setup(item):
    print("BEFORE", item)
    yield
    print("AFTER", item)


@pytest.fixture
def a_fixture():
    import time
    time.sleep(2)
    return "nothing"

foo

foo

test_foo.py

def test_foo(a_fixture):
    print("inside test_foo", a_fixture)