I've had stool analysis done by Genova Diagnostics. But if you do research into leaky gut etc, most people find they have some sort of issue just from the description. A food allergy is a gut problem too. Common symptoms showing something's up with your gut:
bloating
windy (I think 15 to 40 farts a day are normal)
diarrhoea
constipation
heartburn
burping
undigested food in stool
nausea
not feeling hungry
feeling hungry all the time
Most people have something wrong with their gut as they eat a standard Western Diet. Not enough fibre, not enough protein and not enough fat.