Thursday, June 27, 2013

Jasmine: A JavaScript Testing Framework

I have been experimenting more with JavaScript frameworks lately. Being fond of the Test Driven Development methodology, I came across Jasmine. Here is how the site defines it: Jasmine is a behavior-driven development framework for testing JavaScript code. It does not depend on any other JavaScript frameworks. It does not require a DOM. And it has a clean, obvious syntax so that you can easily write tests.
If you have not already, download Jasmine from
After you decompress the downloaded file you see this directory structure.

As you can see, the SpecRunner.html file is your user interface that is simply run from a web browser. The spec folder will hold, as you guessed, your specification code—what you want your implementation to do. The src folder will contain the code you are testing.
The JavaScript includes in the SpecRunner.html file need to be set as such:

What I wanted to do was to test how to sort a JavaScript array based on a date element in the array. So let’s start with the spec file. I named my spec DateSortSpec.js and placed it in the spec directory. Here is the DateSortSpec.js:

Next, the source code file,DateSort.js, goes in the scr directory:

OK, with basic structure in place let's do a sanity check and make sure we get a failing test result:

Now let’s get the “should show Health for a Friend title with ascending sort” spec to pass. First, create a function that will sort ascending by date. What I did was to utilize the JavaScript array.sort method passing in a compare function.

Now reload the browser and the spec passes.

Next we will add the spec to sort descending.

Reload the browser and we see the spec fail as we have not implemented any code for the spec.

So, the next step is clear. Implement enough code to pass the spec. Here I again use the JavaScript array.sort method passing in a function for a descending comparator.

Refresh the browser again and bang!

As you can see using Jasmine is pretty straight forward. Setup is a matter of expanding the compressed file. Moreover, if one has a web browser and text editor you a ready to code the specs and source code.

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