From ea000ead66f0a809c0d7768202185598f7595f8b Mon Sep 17 00:00:00 2001
From: timmycheng1221 <cksh11336@gmail.com>
Date: Wed, 28 Oct 2015 23:52:37 +0800
Subject: [PATCH 1/4] 6 Write at least one passing test (PR green light)

---
 calculator.js           |  1 +
 test/test_calculator.js | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/calculator.js b/calculator.js
index caf34db..18d6383 100644
--- a/calculator.js
+++ b/calculator.js
@@ -12,4 +12,5 @@ function substract(num1, num2){
 }
 
 module.exports.add = add;
+module.exports.substract = substract;
 module.exports.isNumber = isNumber;
diff --git a/test/test_calculator.js b/test/test_calculator.js
index 13f6205..84fecab 100644
--- a/test/test_calculator.js
+++ b/test/test_calculator.js
@@ -7,4 +7,14 @@ describe('Calculator', function(){
       assert.equal('2', cal.add(1, 1));
     })
   })
+  describe('substract', function(){
+    it('substract', function(){
+      assert.equal('0', cal.substract(1, 1));
+    })
+  })
+  describe('isNumber', function(){
+    it('isNumber', function(){
+      assert.equal(true, cal.isNumber(1));
+    })
+  })
 })

From b62c64afd9cf290dd51a8f28985b48d7d1e89446 Mon Sep 17 00:00:00 2001
From: timmycheng1221 <cksh11336@gmail.com>
Date: Wed, 28 Oct 2015 23:58:02 +0800
Subject: [PATCH 2/4] Add multiple feature and test

---
 calculator.js           | 5 +++++
 test/test_calculator.js | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/calculator.js b/calculator.js
index 18d6383..cf799f9 100644
--- a/calculator.js
+++ b/calculator.js
@@ -11,6 +11,11 @@ function substract(num1, num2){
   return num1 - num2;
 }
 
+function multiple(num1, num2){
+  return num1 * num2;
+}
+
 module.exports.add = add;
 module.exports.substract = substract;
+module.exports.multiple = multiple;
 module.exports.isNumber = isNumber;
diff --git a/test/test_calculator.js b/test/test_calculator.js
index 84fecab..7700e52 100644
--- a/test/test_calculator.js
+++ b/test/test_calculator.js
@@ -12,6 +12,11 @@ describe('Calculator', function(){
       assert.equal('0', cal.substract(1, 1));
     })
   })
+  describe('multiple', function(){
+    it('multiple', function(){
+      assert.equal('9', cal.multiple(3, 3));
+    })
+  })
   describe('isNumber', function(){
     it('isNumber', function(){
       assert.equal(true, cal.isNumber(1));

From 160cc45ee927155ff7235f1beab4624f66e40100 Mon Sep 17 00:00:00 2001
From: timmycheng1221 <cksh11336@gmail.com>
Date: Thu, 29 Oct 2015 00:01:03 +0800
Subject: [PATCH 3/4] Add negative path tests for isNumber function

---
 test/test_calculator.js | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/test/test_calculator.js b/test/test_calculator.js
index 7700e52..a6e92d3 100644
--- a/test/test_calculator.js
+++ b/test/test_calculator.js
@@ -19,7 +19,12 @@ describe('Calculator', function(){
   })
   describe('isNumber', function(){
     it('isNumber', function(){
-      assert.equal(true, cal.isNumber(1));
+      assert.equal(true, cal.isNumber('1'));
+    })
+  })
+  describe('isNotNumber', function(){
+    it('isNotNumber', function(){
+      assert.equal(false, cal.isNumber('1a'));
     })
   })
 })

From 4569bb234fd02a78b70cf2095b1a81f18e60a75b Mon Sep 17 00:00:00 2001
From: timmycheng1221 <cksh11336@gmail.com>
Date: Thu, 29 Oct 2015 01:08:03 +0800
Subject: [PATCH 4/4] Stubbing with Sinon.js(random number)

---
 calculator.js           | 5 +++++
 package.json            | 1 +
 test/test_calculator.js | 7 +++++++
 3 files changed, 13 insertions(+)

diff --git a/calculator.js b/calculator.js
index cf799f9..f7ae484 100644
--- a/calculator.js
+++ b/calculator.js
@@ -15,7 +15,12 @@ function multiple(num1, num2){
   return num1 * num2;
 }
 
+function randomSubstract(num){
+  return num - Math.random() ;
+}
+
 module.exports.add = add;
 module.exports.substract = substract;
 module.exports.multiple = multiple;
 module.exports.isNumber = isNumber;
+module.exports.randomSubstract = randomSubstract;
diff --git a/package.json b/package.json
index d727f6d..b723763 100644
--- a/package.json
+++ b/package.json
@@ -9,6 +9,7 @@
   "license": "MPLv2",
   "dependencies": {
     "mocha": "~2.3.2"
+    "sinon": "~1.17.2"
   },
   "repository":{}
 }
diff --git a/test/test_calculator.js b/test/test_calculator.js
index a6e92d3..53c3f52 100644
--- a/test/test_calculator.js
+++ b/test/test_calculator.js
@@ -1,4 +1,5 @@
 var assert = require('assert');
+var sinon = require('sinon');
 var cal = require('../calculator.js')
 
 describe('Calculator', function(){
@@ -27,4 +28,10 @@ describe('Calculator', function(){
       assert.equal(false, cal.isNumber('1a'));
     })
   })
+  describe('randomSubstract', function(){
+    it('randomSubstract', function(){
+      var cb = sinon.stub(Math, 'random').returns(0.1);
+      assert.equal(0.9, cal.randomSubstract(1));
+    })
+  })
 })