Can you explain what the term 'fixture' means in testing?

In testing, the term "fixture" refers to a prepared state of the test environment or a set of data necessary for the correct execution of a test. This can include, for example, creating a test database with the required records, setting up the environment, initializing objects, or starting services.

Fixtures help ensure repeatability and isolation of tests so that each test begins with a predictable state.

An example in Python using pytest:

import pytest

@pytest.fixture
def sample_data():
    return {'user': 'test', 'password': '1234'}

def test_login(sample_data):
    assert sample_data['user'] == 'test'

Here, sample_data is a fixture that provides the test with the necessary data.