Unfortunately Sebastian Bergmann decided to remove PHPUnit_Story from future PHPUnit versions. Thanks to elvan for pointing me to the relevant comment. As an alternative Behat has been suggested but it seems too bloated for me TBH. There is also PHPSpec but it's non flexible enough for me and tightly bound with English language (What's the purpose of using DSL if customers can't speak English). Since both frameworks are quite young I think I'll just stick to PHPUnit and see what's going on on the BDD frameworks arena. Even PHPUnit_Story parts of this entry are going to be deprecated soon, rest is still valid! When doing TDD, please write tests with design and behaviour of application in mind instead of testing single functions.
A dropdown list can be used to select a value, based on which we can filter the data to be displayed. For example, the extension page has a dropdown list to filter the displayed extensions according to the selected category.