I'm working with Magento 2 as a project in school and I'm currently writing tests in Casper.js to test the client and have a hard time to grab information from the messages, for example "You product to your shopping cart." which is located inside the div with "data-bind="html: message.text"" attribute in it. It would be much easier if I were able to add a custom class or id to that div instead.
Any ideas on how to do this the best way? Thanks
I'll update my initial question.
Speaking of containers and blocks, where can I find the div? I am trying to use a module to add a class to this div.
You need to modify phtml file of core( if you're not working on your custom theme), which is not a good idea.
The best approach is to override core layout and define your custom phtml. Visit the following for more detail.