Detecting item passive abilities?

I have an item with a custom passive ability. I know to do it's effect, however, I don't understand how to make a trigger to detect if the hero has it.

In general, how do you detect item passive abilities? I have absolutely no idea how.

AFAIK there is no way to detect if a specific item has a specific ability.
Why can't you just detect whether the item in question is in hero's inventory?

I think you can give the item a buff giving passive, and check for the buff. Technically should work, but I haven't tried it.

Another way to go about it, if you don't want to have unneeded buffs on your hero interface, would be setting hero's custom value to indicate that he has a passive ability.

Items work like that: When a hero picks up an item all the abilities of the item are added to the hero. When the item is dropped, the ability is removed again -> UnitHasAbility will return true when a hero has an item with that passive ability.

So it's really incredibly easy to do a check with triggers.

...and that's why you can always disable an item ability through unit-remove abilit, right?

correct.

Oh, I see. So even if I used a "Unit has ability equal to (Item Passive)", it will still count as the item's passive ability? (Restating your answer so I understand what your talking about.)

Yes. And as soon as the item is dropped you'll get false again.