How do I test my custom error pages to ensure they are working correctly?

Testing involves intentionally triggering errors. You can simulate errors by: 1) Throwing exceptions in your controller actions. 2) Requesting non-existent routes to trigger 404 errors. 3) Modifying your `web.config` to simulate server errors. 4) Using browser developer tools to simulate network errors. Verify that the correct custom error page is displayed for each scenario and that error details are logged appropriately.