Add some testing

Issue: #176

.travis.yml

@@ -1,12 +1,12 @@
 language: node_js
 
+node_js:
+  - "node"
+
 addons:
   apt:
     update: true
 
-node_js:
-  - "node"
-
 notifications:
   webhooks:
     urls:
@@ -17,9 +17,11 @@ notifications:
 
 install:
   - npm install jshint PrettyCSS js-beautify html-linter -g
+  - npm install
   - bundle install
 
 script:
   - ./lint.sh
   - bundle exec danger
   - bundle exec jekyll build
+  - npm test

package.json

@@ -0,0 +1,8 @@
+{
+  "scripts": {
+    "test": "mocha"
+  },
+  "devDependencies": {
+    "mocha": "^5.2.0"
+  }
+}

test/test-main.js

@@ -0,0 +1,8 @@
+var assert = require('assert');
+describe('Array', function() {
+  describe('#indexOf()', function() {
+    it('should return -1 when the value is not present', function() {
+      assert.equal([1,2,3].indexOf(4), -1);
+    });
+  });
+});