# Unit Testing [TDD](https://blog.risingstack.com/getting-node-js-testing-and-tdd-right-node-js-at-scale/) is an essential part of any software development cycle. Here's a story from my past which relates its importance: > I created a filter module for products just like amazon or flipkart have. I tested it well on my machine and it was working great. Then came the day of live demo to our client, where this filter suddenly stopped working! It was doing nothing in our staging env and it was kind of embarrassing. The next day, I decided to create unit tests for each every function that I wrote. As developer we should feel confident in our code's ability to run well, therefore, we must learn to love the feeling of having a watertight app that comes with automated testing. Apart from my stories let us start a real example. You can follow [AngularUnitTestDemo](https://github.com/Mohammed-Aadil/AngularUnitTestDemo) on github or clone a local copy to begin with. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://shoppinpal.gitbook.io/docs-shoppinpal-com/5.-the-frontend/unit-testing.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.