honestly "cat tests" aren't always accurate anyways so don't feel like you're missing out on something that would give you foolproof insight. if you are able to meet and play with the dog, a possible tell is how they react towards small quick objects like a ball moving across the floor. sometimes it's easy to tell the difference between happy excited ball play vs very intense focus and drive towards the moving object that would likely translate to a small animal like a cat. you can also try to tell how well they respond to correction. obviously being corrected by you is different than being corrected by a cat, but some dogs are much more docile and submissive to corrections and others can get overstimulated by it and it can actually increase their energy and intensity. and then not to state the obvious but when you bring this dog home make sure to do very slow introductions, set up a baby gate if possible so they are able to observe each other from a distance, keep a leash dragging so you are able to quickly grab the dog if needed, make sure the cat has places in the house it can access away from the dog, etc.