The function of a testing framework in software development practices is to provide a structured environment for testing applications to ensure they perform as expected. It encompasses tools, libraries, and guidelines that facilitate the creation and execution of tests, such as unit tests, integration tests, and end-to-end tests. A robust testing framework aids in automating repetitive testing tasks, enhancing code quality by catching bugs early in the development process. Overall, testing frameworks are instrumental in delivering reliable software products and enhancing the development workflow.