What is a fixture in testing?

A fixture in testing is a set of preconditions and data necessary to run a test. It prepares the test environment, for example, by creating objects, configuring the database, and setting up the environment so that tests are isolated and reproducible.

For example, in web application tests, a fixture might create a user with specific permissions and populate the database with test data before executing the test.

In automation, fixtures are often implemented using special methods or annotations, such as @Before in JUnit or fixtures with the @pytest.fixture decorator in pytest.