Artisan Tinker is a nice way to quickly check some commands without making changes the code. You launch artisan tinker and can do things like database queries, check if some functions are working etc. But there's one thing to keep in mind.
[caption id="attachment_1365" align="alignnone" width="740"] Here's an example of my local Artisan Tinker launch[/caption]
If you launch Tinker, it works with the instance of the app at that particular moment. So if you find something not working, then go to your code and fix/deploy it, then you need to restart tinker to try again. Only then you will get new instance of the app which you can test.
Interestingly, Tinker is not mentioned in the official Laravel documentation, but here's an article about how to use it.