The most fool proof way to know when chicken is cooked through is to check with a meat thermometer. Ensure that the thickest part of the meat has reached an internal temperature of 165 degrees F. If you don't have a meat thermometer, you can do the "finger test" or "poke test" to the chicken. Simply poke the chicken with your finger and notice how it feels. If it is bouncy with some give-and-take, the chicken is not cooked. If the chicken is firm it should be fully cooked. Lastly, my tried and true test is to just cut into a piece to take a peak. If the meat is white with no pink, you're good-to-go.