verify(graphDisplay, times(1)).addEventHandler(eq(NodeDragEvent.TYPE),
argument1.capture());
NodeDragHandler nodeDragHandler = argument1.getValue();
nodeDragHandler.onDrag(new NodeDragEvent(node, sourceLocation.getX(),
sourceLocation.getY(), targetLocation.getX(), targetLocation
.getY()));
ArgumentCaptor<UndoableCommand> argument2 = ArgumentCaptor
.forClass(UndoableCommand.class);