[RFR] Test directives

 - [x] Write tests for dropper
 - [x] Write tests for overlay
 - [x] Write tests for repository
 - [x] Write tests for draggable
 - [x] Write tests for droppable
 - [x] Write tests for focus-me
 - [x] Write tests for navbar-item
 - [x] Write tests for property-value
 - [x] Write tests for tree-node
 - [x] Write tests for tree