coffee will help you to stay awake so you can take a test if that's what you mean and getting enough sleep before it at least 8 hours and having enough food in your body helps you to not be tired so you can focus on taking a test hope this helped good luck on it!!! :)
Key Ingredient: Flavonoids and Caffeine Test Help: Focus and Concentration
We've all heard for a while now that in small quantities, 75% cacao content or higher dark chocolate can lower blood pressure and cholesterol because of its powerful antioxidant properties from the flavonoids. But one of the best uses of dark chocolate comes from its natural stimulant: caffeine. Why? It can help you focus your energy. Beware, though. Too much caffeine will send you through the roof and can actually work against you when you sit down to test. So eat the dark chocolate in isolation.
Depends on how you react to choclate. If you become extremely hyper after a load of choclate then no it won't affect your attentivness, butt if you tend to be a more focused agile person that needs a boost from something other than cofee and chcolate is within arms reach indeed it is the better choice.