[exaldb]

The best way is probably to ask them to show you that it’s working and explain how they know that’s the intended or correct behavior.

Another way would be to learn some technical details so you understand what they’re saying and doing instead of writing yourself off as non-technical.

A worse but doable way is to have someone with expertise check their work. That only makes sense if you don’t trust your developers which is a pretty bad situation.

Your question is weird because it’s sort of like asking “How do you know if a contractor is building a house properly when you don’t know anything about building houses?”