factory.js

angular.module("xciteServices", [])
.factory('CartService', function() {
	// Factory for Cart Items
	var cartItems = angular.copy(window.Globals.CartItems);
	return {
		// private function to find item with itemId
		_findItem: function(itemId) {
			var index = -1;
			for (var i in cartItems) {
				if (cartItems[i].id === itemId) {
					index = i;
				}
			}
			return index;
		},
		
		// private function to find total of cart items
		_getTotal: function() {
			var total = 0.0;
			for (var i in cartItems) {
				total += parseFloat(cartItems[i].value);
			}
			return total;
		},

		getItems: function() {
			return cartItems;
		},

		// removes an item on cart with the matching id
		removeItem: function(itemId) {
			var index = this._findItem(itemId);
			if (index > -1) {
				cartItems.splice(index, 1);
			}
		},

		// adds an item of schema id, value and label to cart 
		addItem: function(item) {
			var index = this._findItem(item.id);
			var total = this._getTotal();
			var value_to_add = item.value;
			
			/* if the item is a discount and if discount > cart total
			 * set value correctly so that cart doesn't get negative
			 */
			if (item.value < 0) {
				if (total < Math.abs(item.value)) {
					value_to_add = -1 * total;
				}
				if (total === 0) {
					value_to_add = 0;
				}
			}

			// if item already added, dont change else add
			if (index === -1) {
				cartItems.push({ id: item.id, label: item.label, value: value_to_add });
			}
		}

	}
})

describe('services', function() {
    beforeEach(module('xciteServices'));

    describe("cart service", function() {
        var CartService;
        var window = {Globals: {CartItems: {}}};

        beforeEach(inject(function (_CartService_) {
            CartService = _CartService_;
        }));

        it("should return blank total correctly", function() {
            expect(CartService._getTotal()).toBe("0");
        });

    });

});