We test the main types of grills differently, but for most, we include a high-heat test like searing steak or grilling burgers, a medium, indirect heat test like grilling a whole chicken for more than an hour and a low-and-slow test with racks of ribs.
To determine what should be the best outdoor barbecue grill, we collect data including total cooking time, temperatures inside the grill and temperature inside separate pieces of meat. All that information helps us find where grills might have hot spots or thermometer inconsistencies.
I use the InfiRay P2 Pro to test how fast the grills heat up and if the heat is even. It only works as the grills heat up because the top temperature is too high, but it gives me a good idea of how well each grill spreads the needed heat.
There's also a fair amount of (read: so much) blind taste testing, lively debate and voting among our editors and families, in addition to the data we gather about grilling temperatures and cooking times. You might think it would be more fun than work to eat delicious food while discussing the merits of a grill, and you'd be right.
If you're interested in any particular method of testing, we've got that, plus our recommendations for cooking with kamado grills, portable grills and charcoal grills ready for your perusal. Happy grilling.