Glad you love your FreeNAS but when/if you have a question, please post your system configuration or better yet, make it part of your tag line. It will certainly save time if it is something that needs to be considered. If you ask what I'd consider a Lazy Question (something that a quick Google search would find) then some folks might be irritated at that. Always do a Google search, you might be surprised what comes up.
A test machine doesn't need ECC RAM, and as gpsguy said, Virtual Machine. There are free VM applications which work very well. I prefer VMWare Workstation (not free) or VMWare Player (free). Others like Virtualbox. If you have 8GB of RAM in your machine then you can run these applications bt more RAM is better of course. And then again, you can use virtually any unused PC that has 8GB RAM, a single hard drive and a USB Flash drive to run FreeNAS for testing purposes.