How do you test sugar sweetness without using person or an animal?

You can use a Brix refractrometer to measure the percent of sugar in aqueous solutions. The Brix refractrometer is an optical instrument that employs the measurement of refractive index of the sample and converts it to % Brix concentration units. One degree Brix is 1 gram of sucrose in 100 grams of solution and represents the strength of the solution as percentage by mass. If the solution contains dissolved solids other than pure sucrose, then the degree Brix approximates the dissolved solid content. This test is traditionally used in the wine, sugar, carbonated beverage, fruit juice, and honey industries.