duck test
A form of logical, intuitive reasoning to deduce the nature of an uncertain thing or situation, usually in the absence or in spite of concrete evidence. Adapted from the saying, "If it looks like a duck, swims like a duck, and quacks like a duck, then it's probably a duck." You aren't sure whether he likes you? Just use the duck test—if he's showing you all the signs of being interested, then he most likely is.