Fixtures

Fixtures are typed dependency providers. A test requests a fixture by using its name as a function parameter.

Return-value fixtures

from testenix import fixture


@fixture
def customer_id() -> int:
    return 42


def test_customer(customer_id: int) -> None:
    assert customer_id > 0

Cleanup with generators

Synchronous and asynchronous generator fixtures run cleanup after the consumer:

from collections.abc import AsyncIterator

from testenix import fixture


@fixture
async def client() -> AsyncIterator[Client]:
    value = await Client.connect()
    try:
        yield value
    finally:
        await value.close()

Setup, call, and teardown are separate result phases. A teardown failure remains visible even when the test body passed.

Fixture dependencies

Fixtures can request other fixtures:

@fixture
def database_url() -> str:
    return "sqlite:///:memory:"


@fixture
def repository(database_url: str) -> Repository:
    return Repository(database_url)


def test_empty_repository(repository: Repository) -> None:
    assert repository.count() == 0

The dependency graph is validated before execution. Missing fixtures and cycles become collection issues instead of hanging the run.

Built-in fixtures

Testenix 0.3 provides two dependency-free, test-scoped built-ins by name:

from pathlib import Path


def test_isolated_file(tmp_path: Path, monkeypatch) -> None:
    target = tmp_path / "value.txt"
    target.write_text("ok", encoding="utf-8")
    monkeypatch.setenv("TESTENIX_EXAMPLE", "enabled")
    assert target.read_text(encoding="utf-8") == "ok"

tmp_path is a fresh pathlib.Path removed during teardown. monkeypatch supports reversible object/attribute and dotted-import setattr, setenv, and idempotent undo. Changes are restored in LIFO order even when the test fails. Other pytest monkeypatch operations and pytest built-ins such as capsys, caplog, and request are not native Testenix fixtures.

Autouse fixtures

Use autouse=True when setup and cleanup must apply to every test that can see a fixture:

@fixture(autouse=True)
def isolated_environment(monkeypatch):
    monkeypatch.setenv("APP_ENV", "test")
    yield

Explicitly requesting the same fixture still resolves one cached value for the test. A local fixture definition overrides a visible imported definition with the same name before Testenix chooses which fixtures run automatically.

Scopes

@fixture(scope="module")
def module_resource() -> Resource:
    return Resource()


@fixture(scope="session")
def worker_resource() -> Resource:
    return Resource()

Scope	Lifetime in Testenix 0.3
test	One instance for one concrete test attempt.
module	Shared by normal tests from the module inside one worker.
session	Shared by normal tests assigned to one worker process.

Session scope is currently worker-local, not a single process-global instance. Timed tests run in dedicated processes and therefore receive isolated module/session fixtures.

Custom fixture names

@fixture(name="api")
def build_client() -> Client:
    return Client()


def test_health(api: Client) -> None:
    assert api.health() == "ok"

The custom name changes dependency lookup without changing the Python function.