Add tests for drag & drop

[chasenlehara]

Currently, there is no test coverage for the code here:

a2jdeps/elements/a2j-template/a2j-template.js

Lines 16 to 87 in fc4d9c4

	'li dragstart': function (el, evt) {
	evt.stopPropagation()
	let $el = $(el)
	let dt = evt.dataTransfer
	dt.effectAllowed = 'move'
	dt.setData('text/html', null)
	this.viewModel.attr('dragItemIndex', $el.index())
	$(this.element).find('element-options-pane').hide()
	},
	'li dragenter': function (el, evt) {
	evt.stopPropagation()
	let $el = $(el)
	let dropIndex = this.viewModel.attr('dropItemIndex')
	// add placeholder class to the dragged element (dropIndex is null) and
	// when the element receiving the dragenter event is at a different index
	// than the dragged element (dragenter is fired multiple times).
	if (dropIndex == null || (dropIndex != null && dropIndex !== $el.index())) {
	this.viewModel.setDragPlaceholderFlag()
	}
	},
	'li dragover': function ($el, evt) {
	evt.preventDefault()
	let dt = evt.dataTransfer
	dt.dropEffect = 'move'
	},
	// this event won't be dispatched if the source node is moved during the
	// drag, causing the placeholder to stay visible after the elemet has been
	// dropped.
	'li dragend': function () {
	this.viewModel.removeDragPlaceholderFlag()
	this.viewModel.attr({
	dragItemIndex: null,
	dropItemIndex: null
	})
	},
	'li drop': function (el, evt) {
	evt.stopPropagation()
	this.viewModel.removeDragPlaceholderFlag()
	let $el = $(el)
	this.viewModel.attr('dropItemIndex', $el.index())
	this.viewModel.attr({
	dragItemIndex: null,
	dropItemIndex: null
	})
	},
	// to workaround the issue with the `dragend` event not being dispatched,
	// we have to make the document a valid drop target, in order to do that
	// we need to set listeners for `dragstart` and `dragover` events.
	'{document} dragstart': function () {},
	'{document} dragover': function ($el, evt) {
	evt.preventDefault()
	this.viewModel.removeDragPlaceholderFlag()
	},
	// if a template is not being droppped within the boundaries of one the
	// items, we need to make sure the placeholder class is removed anyways,
	// the dragged item will remain at its last valid position.
	'{document} drop': function ($el, evt) {
	evt.preventDefault()
	this.viewModel.removeDragPlaceholderFlag()
	},

We should be able to use FuncUnit’s drag method or Syn, which is what FuncUnit uses under the hood and provides many more options.