Their are test that are on youtube of honeys that are cut / diluted with corn or sugar syrup. But for honey that may be derived by the bees from process or refined sugars rather than nectars, microscopic identification needs to be used on the raw honey to see that the pollens that the sample contains are in the range for the nectar source. Also the honey can be broke down to see if the sugars and minerals are in the appropriate proportions of the type of nectar the bees were gathering.