It is vital to have some sort of local test environment for Joomla or for any website project you have.
Ideally you always work locally, then move all your work to the live site when completed. If you are doing your development on a live site, or doing upgrades and feature changes to a live site, you are playing with fire and it’s only a matter of time before you burn yourself.
I use MAMP as I use Mac and find it very simple, lightweight, and easy to use. If you are on a PC you can try XAMPP or JSAS. YYMV on what you prefer. I think XAMPP is a bit cumbersome, and has a slight learning curve. MAMP is as easy as you can get, and JSAS is right in the middle of the two.
No matter what you prefer, make sure you stick to it. Nothing is worse then doing a Joomla upgrade, and finding your site offline to the world and with no clear path to fix it. Do it locally, before you do it publicly.