Can you explain what is meant by fixture in the context of testing with pytest?

In a pytest fixture — it is a special function that prepares and provides the necessary resources or data for tests. It allows setting up the environment before the test runs and cleaning it up afterward, ensuring code reuse and test isolation.

For example, if you need to connect to a database or create test data, a fixture will create this once and pass it to tests via parameterization:

import pytest

@pytest.fixture
def sample_list():
    return [1, 2, 3, 4]


def test_sum(sample_list):
    assert sum(sample_list) == 10

Here, sample_list is a fixture that returns a list used in the test. This simplifies maintenance and makes tests more readable.