Are there test that can prove or disprove epilepsy?

Generally yes. It is easier to prove something exists, if you have an eeg monitor in place and the epileptic event is caught - it is generally considered proven. However, depending on the type, duration & timing of eeg monitoring etc, does not mean one eeg disproves epilepsy. It can be missed. In some cases video monitored eegs are done for 72 hours to rule out non-epileptic seizures (pseudoseizures).