I don't know that you can test the recovery disc/USB, but as said backing up is the way to go.
Something like ACRONIS TRUE IMAGE.
I have mine automated to backup once per week, Incremental method, and it deletes older backups so I never worry about it. If you don't have an internal drive you can set Acronis TI to backup once it detects you attaching a USB hard drive (if it missed its backup date).
Other:
I also use SyncbackSE Free for specific folders. That's on a daily basis.
Other:
I setup a WDMYCLOUD for my house and my sisters house. It's an external HDD that attaches to your ROUTER so can be accessed by all local computers and devices. I backup to it from the laptop, and also use it to store videos and play those via a media box attached to the HDTV.