TestHelpers.draggable = {
	// todo: remove the unreliable offset hacks
	unreliableOffset: $.ui.ie && ( !document.documentMode || document.documentMode < 8 ) ? 2 : 0,
	drag: function(handle, dx, dy) {
		$(handle).simulate("drag", {
			dx: dx || 0,
			dy: dy || 0
		});
	},
	testDrag: function(el, handle, dx, dy, expectedDX, expectedDY, msg) {
		var offsetAfter, actual, expected,
			offsetBefore = el.offset();

		TestHelpers.draggable.drag(handle, dx, dy);
		offsetAfter = el.offset();

		actual = { left: offsetAfter.left, top: offsetAfter.top },
		expected = { left: offsetBefore.left + expectedDX, top: offsetBefore.top + expectedDY };

		msg = msg ? msg + "." : "";
		deepEqual(actual, expected, 'dragged[' + dx + ', ' + dy + '] ' + msg);
	},
	shouldMove: function(el, why) {
		TestHelpers.draggable.testDrag(el, el, 50, 50, 50, 50, why);
	},
	shouldNotMove: function(el, why) {
		TestHelpers.draggable.testDrag(el, el, 50, 50, 0, 0, why);
	},
	testScroll: function(el, position ) {
		var oldPosition = $("#main").css('position');
		$("#main").css('position', position);
		TestHelpers.draggable.shouldMove(el, position+' parent');
		$("#main").css('position', oldPosition);
	},
	restoreScroll: function( what ) {
		if( what ) {
			$(document).scrollTop(0); $(document).scrollLeft(0);
		} else {
			$("#main").scrollTop(0); $("#main").scrollLeft(0);
		}
	},
	setScroll: function( what ) {
		if(what) {
			// todo: currently, the draggable interaction doesn't properly account for scrolled pages,
			// uncomment the line below to make the tests fail that should when the page is scrolled
			// $(document).scrollTop(100); $(document).scrollLeft(100);
		} else {
			$("#main").scrollTop(100); $("#main").scrollLeft(100);
		}
	},
	border: function(el, side) {
		return parseInt(el.css('border-' + side + '-width'), 10) || 0;
	},
	margin: function(el, side) {
		return parseInt(el.css('margin-' + side), 10) || 0;
	}
};