Front-End Testing: A Comprehensive Guide

Slow loading speed, high bandwidth consumption, and other performance issues on the client-side can be deal-breakers that prevent users from getting the most out of your product. For this reason, development teams should incorporate front-end testing in their workflow to ensure users have a seamless experience with their products.

This guide covers everything you should know about front-end testing as an integral part of your quality assurance efforts and overall development lifecycle.

Read along or jump ahead to the section that interests you most. If you already know that you need front end testing, learn how Perfecto Scriptless can help your team get started.

What Is Front End Testing?

Front end testing is performed to check the functionality and usability of an application’s GUI. It usually involves validating menus, forms, buttons, and other elements of the application that are visible to end-users.
 

Combining the properties to reduce the bandwidth and download time.

element { 

 background: #fff url(image.gif) no-repeat top left;

}

Minifying CSS and Script Files

Minifying is an optimization technique that involves removing all space characters in the CSS and script files. It helps reduce the total size of your front end code files, hence reducing the download time upon a client request.

While space and indent characters are important for code cleanliness and readability, they expand the file size, thereby increasing the load time. A good way of minifying the files is by using tools such as Google Minify.

Image Optimization

While it is important to use quality imagery, the high resolution can increase the load time significantly. This is because it costs more bandwidth and increases the load time. The most effective way of optimizing images without loss of quality is by using image compression tools such as Kraken, Optimus, and Optimizilla.

Another image optimization strategy is to avoid scaling images in HTML. When you need a 100x100px image, for instance, do not create a 1000x1000px image then scale it in HTML. Additionally, avoid using images to display text content because it will also increase the page load time.

Other effective front end optimization strategies include:

• Using a Content Delivery Network (CDN).
• Implementing GZip file compression.
• Putting scripts at the bottom of your pages.
• Using external script files.
• Eliminating duplicate scripts.
• Reducing Domain Name System (DNS) lookups.
• Minimizing cookie size.
• Prefetching links and images for quicker access.
• Avoiding redirects whenever possible.
• Making Ajax cacheable.
• Turning off entity tags.

Following the above tips to implement your application’s front-end code will go a long way to improving its overall performance. The process of creating specs and modifying steps involved in a test case is pretty straightforward.
 

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Overcoming Common Front End Testing Challenges

This section takes a closer look at four of the most common front end testing challenges and offers some actionable pointers on how to address the challenges.

Determining the Most Important Front End Elements

Front end testing usually involves testing dozens of UI elements. These include graphics, visible text, formatting, and layout (CSS) as well as functional elements such as buttons, forms, and links. The testing process involves identifying how quickly these features load, how responsive they are to user actions, and how quickly they can execute user requests.

To identify the most important front end features for testing, you can assign rough priorities to the elements. Ideally, you can start by ensuring that basic text and page loads correctly, with key elements placed in the right location. Second, ensure all functional elements are visible and fully responsive. Finally, verify that the graphics and formatting load correctly.

Worth a mention is that the above is just an example of how testers can prioritize their front end testing regime. Some web pages or application modules might require a different approach, such as ensuring graphics load quicker. The most important thing is to ensure the application loads asynchronously. If possible, no UI element should wait for another to load for it to become visible to users.

Simulating the Real-World Environment

This is arguably one of the most common challenges when executing performance-based tests. In most cases, the test environment is controlled, which means the application is not tested under ideal production conditions.

While it is impossible to match the exact user environment, testing teams can set up cases that accurately reflect real-world conditions. This would involve customizing environmental factors that affect page performance.

For instance, you can increase the load on the application in such a way that it reflects concurrent access and multiple user requests to the system. Alternatively, you can limit available memory, CPU performance, or connection speed on the client system.

If you can model these conditions in your test cases, there’s a decent chance that you will reflect the actual production environment. The adjustments you make on the front end will also improve performance in common use cases.

Identifying Where a Problem Lies: Front End or Back End?

It is not always easy to identify whether a problem is on the client-side or server-side. When an application fails to display a particular element, there could be an issue with the front end code, or something could be wrong on the back end, preventing the server or CDN from delivering content.

A good way to identify where the errors lie is by using front end performance metrics that mark early interactions and those that indicate completed actions. When using a metric such as Time to First Byte (TTFB), which is the time between a client request and the arrival of the first byte on the browser, you can easily identify issues outside the browser environment.

TTFB is an effective benchmark for separating server response time and connectivity speed from front end issues. If the TTFB is short, but there’s a huge delay before the interactive content is loaded, then there’s reasonable evidence to conclude that the delays are on the front end.

Choosing an Appropriate Front End Testing Tool

Today’s software testing market is filled with tons of tools from different vendors. This makes it hard for development teams to pick one that works best for their testing needs and development workflows.

The most important step when selecting a testing tool, whether free or commercial, is assessing the features it provides. Ideally, a good front end testing tool offers the following features:

• Easy creation of test scripts.
• Insight into front end performance metrics.
• Screenshot capturing and image comparison capabilities for UI regression testing.
• Great reporting capabilities.
• Codeless automation for quicker and efficient testing.
• Seamless integration into the CI/CD pipeline.

Bottom Line

It is important for development teams to integrate front end testing into their larger continuous testing pipeline. This helps them deliver quality experiences to users without compromising the time of release. With an efficient testing plan coupled with a great testing tool, you can easily identify and fix performance issues on the client side before releasing the application to production.

Perfecto Scriptless enables teams to do codeless front-end testing for web and mobile applications at enterprise scale. This codeless automation tool can be easily integrated into your CI/CD workflow within a unified dashboard.

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