I have never done a patch test and I've used pretty much every product out there to color my hair. I'm sure you're SUPPOSED to, but I bet 98% of women don't.
My advice, though, is to use no products the day you color your hair. For example, wash your hair normally on Friday morning, use whatever products you normally do, and then don't wash on Saturday morning. Instead, color your hair. You'll use conditioner after coloring that comes with the color. I generally take a shower at that time (but no shampoo!!). Then Sunday you can get up and do your regular routine. Your hair color will last longer and stay more shiny/vibrant if you use a color shampoo rather than a regular one.