There wouldn't be any Drupal site that doesn't have forms on it - Drupal being a CMS, forms have always been an integral part of every Drupal version from start. Forms provide an easy interface to the website users to input information to the site.
Being entry points of user input data into a website, forms are the ideal places where we should handle all validation for that data, guiding the user along the way.
Being an input method, forms are also the most vulnerable parts on a website, that offer hackers easy entry points to your server.
With this inherent risk, we have to thoroughly test each and every form element on a Drupal site so as to make sure that all input is validated and made risk-free.
We have compiled some test cases and checklists to help you get started with testing your Drupal forms. Do check them out: