What is a fixture in pytest? What is its scope? Can a fixture be called from another fixture? What is autouse? Can parameters be passed to a fixture?

In pytest, a fixture is a function that prepares the test environment or data needed for tests. It can create objects, set up state, perform preparatory actions, and release resources after the test.

The scope of a fixture determines how often it is invoked:

• function (default) — the fixture is called for each test.
• class — the fixture is called once per test class.
• module — once per module (test file).
• package — once per package.
• session — once per entire test session.

Yes, a fixture can be called from another fixture by simply specifying its name in the function parameters. This allows building dependency chains.

The autouse=True parameter in the @pytest.fixture decorator means that the fixture will automatically apply to all tests in its scope without explicitly mentioning it in the test parameters.

In pytest, you can pass parameters to a fixture via parameterization using @pytest.mark.parametrize or by using request.param within the fixture during parameterization. This enables running tests with different data sets.

Example of a fixture with parameterization and calling another fixture:

import pytest

@pytest.fixture(scope='module')
def db_connection():
    conn = create_db_connection()
    yield conn
    conn.close()

@pytest.fixture(params=["user1", "user2"])
def user(db_connection, request):
    return db_connection.get_user(request.param)

def test_user_access(user):
    assert user.has_access()

Here, user depends on db_connection, and user itself is parameterized with different values.