Added unit test for problem #2.

Author: WilliamHe

test/spec/2.add2Nums.spec.js

@@ -0,0 +1,130 @@
+/************************************************************
+  * Problem: https://leetcode.com/problems/add-two-numbers/
+    You are given two linked lists representing two non-negative numbers.
+    The digits are stored in reverse order and each of their nodes contain a single digit.
+    Add the two numbers and return it as a linked list.
+
+ * Example:
+    Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
+    Output: 7 -> 0 -> 8
+
+ * Definition for singly-linked list:
+    function ListNode(val) {
+      this.val = val;
+      this.next = null;
+    }
+************************************************************/
+
+describe('Problem 2 - Add two non-negative numbers represented by two linked lists into a number represented by a linked list too', function() {
+    beforeEach(function() {
+        var l1, l2, result;
+    });
+
+    // # Helper tests
+    describe('Helper method tests', function() {
+        it('arrToLList return (2 -> 4 -> 3) for [2,4,3]', function() {
+            var testArr = [2, 4, 3];
+
+            result = add2Nums.arrToLList(testArr);
+            expect(result instanceof ListNode).toBeTruthy();
+            expect(result.val).toEqual(2);
+            expect(result.next.val).toEqual(4);
+            expect(result.next.next.val).toEqual(3);
+        });
+
+        it('lListToArr return [2,4,3] for (2 -> 4 -> 3)', function() {
+            var testlList = new ListNode(2);
+            testlList.next = new ListNode(4);
+            testlList.next.next = new ListNode(3);
+
+            result = add2Nums.lListToArr(testlList);
+            expect(result).toEqual([2, 4, 3]);
+        });
+    });
+
+
+    // # Solution 1: brutal loop tests
+    describe('Solution 1: Intro a stack helper to reversely insert each node into linklist', function() {
+        it('return right sum for 2 nums with same digits num that has not carry num: [2, 4, 3]+[5, 2, 5] => [7, 6, 8]', function() {
+            var l1, l2, result;
+            l1 = add2Nums.arrToLList([2, 4, 3]);
+            l2 = add2Nums.arrToLList([5, 2, 5]);
+
+            result = add2Nums.stackHelper(l1, l2);
+            expect(add2Nums.lListToArr(result)).toEqual([7, 6, 8]);
+
+        });
+
+        it('return right sum for 2 nums with same digits num that has carry num: [2, 4, 3]+[5, 6, 4] => [7, 0, 8]', function() {
+            var l1, l2, result;
+            l1 = add2Nums.arrToLList([2, 4, 3]);
+            l2 = add2Nums.arrToLList([5, 6, 4]);
+
+            result = add2Nums.stackHelper(l1, l2);
+            expect(add2Nums.lListToArr(result)).toEqual([7, 0, 8]);
+        });
+
+        it('return sum should exceeds max input digit num limit with carry num: [2, 4, 9]+[5, 9] => [7, 3, 0, 1]', function() {
+            var l1, l2, result;
+            l1 = add2Nums.arrToLList([2, 4, 9]);
+            l2 = add2Nums.arrToLList([5, 9]);
+
+            result = add2Nums.stackHelper(l1, l2);
+            expect(add2Nums.lListToArr(result)).toEqual([7, 3, 0, 1]);
+        });
+
+        it('return right sum for 2 nums with different digits num: [6, 9, 3]+[9] => [5, 0, 4]', function() {
+            var l1, l2, result;
+            l1 = add2Nums.arrToLList([6, 9, 3]);
+            l2 = add2Nums.arrToLList([9]);
+
+            result = add2Nums.stackHelper(l1, l2);
+            expect(add2Nums.lListToArr(result)).toEqual([5, 0, 4]);
+        });
+
+    });
+
+
+    // # Solution 2: js reference. Utilized js object reference change feature
+    describe('Solution 2: js reference. Utilized js object reference change feature', function() {
+        it('return right sum for 2 nums with same digits num that has not carry num: [2, 4, 3]+[5, 2, 5] => [7, 6, 8]', function() {
+            var l1, l2, result;
+            l1 = add2Nums.arrToLList([2, 4, 3]);
+            l2 = add2Nums.arrToLList([5, 2, 5]);
+
+            result = add2Nums.reference(l1, l2);
+            expect(add2Nums.lListToArr(result)).toEqual([7, 6, 8]);
+
+        });
+
+        it('return right sum for 2 nums with same digits num that has carry num: [2, 4, 3]+[5, 6, 4] => [7, 0, 8]', function() {
+            var l1, l2, result;
+            l1 = add2Nums.arrToLList([2, 4, 3]);
+            l2 = add2Nums.arrToLList([5, 6, 4]);
+
+            result = add2Nums.reference(l1, l2);
+            expect(add2Nums.lListToArr(result)).toEqual([7, 0, 8]);
+        });
+
+        it('return sum should exceeds max input digit num limit with carry num: [2, 4, 9]+[5, 9] => [7, 3, 0, 1]', function() {
+            var l1, l2, result;
+            l1 = add2Nums.arrToLList([2, 4, 9]);
+            l2 = add2Nums.arrToLList([5, 9]);
+
+            result = add2Nums.reference(l1, l2);
+            expect(add2Nums.lListToArr(result)).toEqual([7, 3, 0, 1]);
+        });
+
+        it('return right sum for 2 nums with different digits num: [6, 9, 3]+[9] => [5, 0, 4]', function() {
+            var l1, l2, result;
+            l1 = add2Nums.arrToLList([6, 9, 3]);
+            l2 = add2Nums.arrToLList([9]);
+
+            result = add2Nums.reference(l1, l2);
+            expect(add2Nums.lListToArr(result)).toEqual([5, 0, 4]);
+        });
+
+    });
+
+
+});

test/spec/helpers/2.add2Nums.js

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+add2Nums.arrToLList = function(arr) {
+    var lastNode, newNode;
+    while (arr.length > 0) {
+        newNode = new ListNode(arr.pop());
+
+        if (lastNode) {
+            newNode.next = lastNode;
+        }
+        lastNode = newNode;
+    }
+
+    return newNode;
+};
+
+add2Nums.lListToArr = function(lList) {
+    var curNode = lList,
+    	arr = [];
+
+    while (curNode && typeof curNode.val === "number") {
+        arr.push(curNode.val);
+
+        curNode = curNode.next;
+    }
+
+    return arr;
+};