JavaScript Unit Testing

Modern web applications use various java-script code to provide better interactivity and responsiveness. For example, java-script libraries like JQuery, KnockoutJS, DurandalJS, RequireJS and etc. So now we need to have proper environment for test java-script code. This will be a different challenge than server side testing.

In this demo I'll show how to test small java-script code which will calculate two input values. For testing, I'll use QUnit, which was written by JQuery team to test JQuery.

Create ASP.net MVC internet application. In HomeController add Demo Action and related view.

As you can see I have used HTML5 data bindings with KnockoutJS. Add calculate.js file with following scripts. If you are not familiar with KnockoutJS, you can read my previous posts.

When a user enter Number1, Number2 and press Add, then calculation will happen and total will be shown. Run this application and try it.

Now we have to test java-script code we wrote in calculate.js.

Download QUnit java-script file and QUnit style-sheet file from QUnit site. Add those files to Scripts and Content folders appropriately.
It's better to create tests separately. So we can add a new ASP.net MVC Area called Test.

Add DemoController and Index action and related view. In Index view add refrences for QUnit style sheet and QUnit java-script files. Also we need to add JQuery, Knockout and calcualte.js files, because calculate.js file requires those java-script libraries. Also add two div elements, which requires for QUnit. Give id for those div elements like below.

CalculateTest.js file is the java-script file which we wrote tests. Content of CalculateTest.js file is like below.

The test function and equal functions are specific to QUnit. In this file there's a test scenario called Calculate Test. Within that, I have created CalculateVM and set num1 and num2 appropriately, then call calculate function. After that, test whether total is correct or not. Run the application and go to /Test/Demo/. Result will be like below.

Now change expected value as 31.

Then result will have errors.

You can find the source of this demo in GitHub.