Pytest: making global fixture for entire test run

Question

I have a following structure of modules:

.
├── conftest.py
└── test
    ├── test_one.py
    └── test_two.py

My conftest.py contains a single fixture:

import pytest

@pytest.fixture(scope='session')
def sophisticated_fixture():
    print('\nFixture init')
    yield 42
    print('\nFixture kill')

My test_{one,two}.py tests look like this:

from conftest import sophisticated_fixture


def test_a(sophisticated_fixture):
    assert sophisticated_fixture == 42


def test_b(sophisticated_fixture):
    assert sophisticated_fixture == 42

I would expect that running pytest -s in the top-level directory would run all the tests using the same fixture, as I have defined it as session-level. However, this happens:

============================= test session starts ==============================
platform linux -- Python 3.6.6, pytest-4.0.2, py-1.7.0, pluggy-0.8.0
rootdir: /home/tomasz/example, inifile:
collected 4 items

test/test_one.py 
Fixture init
..
test/test_two.py 
Fixture init
..
Fixture kill

Fixture kill


=========================== 4 passed in 0.01 seconds ===========================

Clearly fixture function is called twice for every test module, and the fixture exits at the very end of the test run.

How can I make my fixture global for the duration of the entire test session?

Answer 1

You do not have to import the fixture in the test file(s). Fixtures are automatically discovered by pytest. Try after removing the below line from test files.

from conftest import sophisticated_fixture