Minecraft Commands – How to Test for a Specific Item with a Unique Name in a Chest

You can use

/testforblock x y z minecraft:chest -1 {Items:[{}]}

Note the extra {} in the Items list. {Items:[{}]} checks if the list of item tags contains an item that matches all the tags present in {}. Obviously, {} does not contain any tags, meaning every item in the game matches this¹.

You can achieve the opposite behavior using {Items:[]}, which will test for an empty list of items.

^{1 Technically, everything matches {}, including Creepers, but the Items tag limits the scope for us.}

Items don't, by default, have any identifying feature that would separate them from another item of the same type. You can swap the position of two levers around in your inventory and your inventory will be in the exact same state.

If you want to test that a specific lever is in the frame, you'll need to make something about it unique. For example, you could give the item you want to test for unique Lore:

/give @p lever 1 0 {display:{Lore:["Key"]}}

And then test for it like this;

/testfor @e[type=ItemFrame,x=-322,y=57,z=-61,r=0] {Item:{id:minecraft:lever,tag:{display:{Lore:["Key"]}}},ItemRotation:5b}