MAP-NCU2015 · cxz91493 · Oct 29, 2015
diff --git a/calculator.js b/calculator.js
@@ -11,5 +11,22 @@ function substract(num1, num2){
   return num1 - num2;
 }
 
+function multiply(num1, num2){
+  return num1 * num2;
+}
+
+function devide(num1, num2){
+	return num1 / num2;
+}
+
+function random(){
+	return Math.floor((Math.random() * 100) + 1);
+}
+
+// exports method for other modules or files to use
 module.exports.add = add;
 module.exports.isNumber = isNumber;
+module.exports.substract = substract;
+module.exports.multiply = multiply;
+module.exports.devide = devide;
+module.exports.random = random;
diff --git a/index.html b/index.html
@@ -18,16 +18,22 @@
   </head>
   <body>
     <h1>Silly Calculator</h1>
-    <input type="text" name="" id="num1" value="1" />
-    <select id="operator" size="1">
-      <option value="add">+</option>
-      <option value="substract">-</option>
-    </select>
-    <input type="text" id="num2" value="1" />
-    <div>=</div>
-    <input type="text" id="ans" value="2" />
-    <button id="go_btn">Go!</button>
-
+    <section>
+      <input type="text" name="" id="num1" value="1" />
+      <select id="operator" size="1">
+        <option value="add">+</option>
+        <option value="substract">-</option>
+        <option value="multiply">*</option>
+        <option value="devide">÷</option>
+      </select>
+      <input type="text" id="num2" value="1" />
+      <div>=</div>
+      <input type="text" id="ans" value="2" />
+      <button id="go_btn">Go!</button>
+    </section>
+    <section>
+      <button id="random_btn">Random number</button>
+    </section>
     <script src="calculator.js" type="text/javascript" charset="utf-8"></script>
     <script src="main.js" type="text/javascript" charset="utf-8"></script>
   </body>

diff --git a/main.js b/main.js
@@ -1,4 +1,10 @@
 window.onload = function(){
+
+  document.getElementById('random_btn').onclick = function(){
+
+      document.getElementById('num1').value = random();
+  }
+
   document.getElementById('go_btn').onclick = function(){
     var num1Str = document.getElementById('num1').value;
     var num2Str = document.getElementById('num2').value;
@@ -16,6 +22,12 @@ window.onload = function(){
     else if (operator == "substract"){
       document.getElementById('ans').value = substract(num1, num2);
     }
+    else if (operator == "multiply"){
+      document.getElementById('ans').value = multiply(num1, num2);
+    }
+    else if (operator == "devide"){
+      document.getElementById('ans').value = devide(num1, num2);
+    }
     else {
       alert("Bad operator!")
     }

diff --git a/package.json b/package.json
@@ -10,5 +10,8 @@
   "dependencies": {
     "mocha": "~2.3.2"
   },
-  "repository":{}
+  "repository": {},
+  "devDependencies": {
+    "sinon": "^1.17.1"
+  }
 }
diff --git a/test/test_calculator.js b/test/test_calculator.js
@@ -1,10 +1,60 @@
+// to use methods from other files we simply use `require` with path name
 var assert = require('assert');
 var cal = require('../calculator.js')
+var sinon = require('sinon')
 
 describe('Calculator', function(){
-  describe('add', function(){
-    it('add', function(){
-      assert.equal('2', cal.add(1, 1));
+	describe('add', function(){
+	    it('add', function(){
+	      assert.equal('2', cal.add(1, 1));
+	    })
+	  })
+
+	describe('substract' , function(){
+	    it('substract', function(){
+			assert.equal('3', cal.substract(5, 2));
+	    })
+	  })
+	/* ------------ Add new feature (× / ÷) ------------ */
+	describe('multiply', function(){
+		it('multiply', function(){
+			assert.equal('20', cal.multiply(4, 5));
+		})
+	})
+
+	describe('devide', function(){
+		it('devide', function(){
+			assert.equal('4', cal.devide(28, 7));
+		})
+	})
+	/* ----------------- negative path ----------------- */
+	describe('negativeAdd' ,function(){
+		it('negativeAdd', function(){
+			assert.notEqual('6', cal.add(2,3));
+		})
+	})
+	describe('negativeSubstract' , function(){
+	    it('negativeSubstract', function(){
+			assert.notEqual('3', cal.substract(5, 1));
+	    })
+	})
+
+	describe('negativeMultiply', function(){
+		it('negativeMultiply', function(){
+			assert.notEqual('21', cal.multiply(4, 5));
+		})
+	})
+
+	describe('devide', function(){
+		it('devide', function(){
+			assert.notEqual('5', cal.devide(28, 7));
+		})
+	})
+	/* --------- Add and mock the random number --------- */
+	describe('random', function() {
+        it('random', function() {
+			sinon.stub(Math, 'random').returns(20);
+            assert.equal('22', cal.add(Math.random(), 2));
+        })
     })
-  })
-})
+})