When developers think of testing, they usually think of the back end of an application and how to make sure it works perfectly. However, front-end testing is as important, if not more so. Webpages aren’t what they used to be. They are more complex, using various scripting elements to make the application better at functionality and feel. Testing the back end is relatively easier. You have full control over the environment and you can subject it to a number of possible conditions, and monitor it based on them. However, that just tells you how your server will respond to the user request and how long it will take to supply the content. What about the front end?
There are a few factors that can help testers gauge the performance of an application’s front end. These include factors such as an application’s overall load time, time for all the responsive elements to load, and time taken for a request to be processed, among others. Based on these factors, delivery teams can carry out front-end performance testing. However, front-end performance testing is challenging to say the least. The process of planning, implementing, and reporting on these tests involves various roadblocks that can make this process cumbersome and long.
Let’s look at some of the pain points DevOps teams face with front-end testing, and how to overcome them.
In the age of CI/CD pipelines, applications need to be delivered at lightning-fast pace. However, testing front-end performance requires time. Without a good strategy in place, the only option for teams is manual testing. And it is as daunting as it sounds. Testers may use various devices to test how an application works in different environments. This is time-consuming and there is always a risk of human error. It’s simply unrealistic to think that manually testing any application will help get rid of every possible bug that an application may have.
Test automation is the obvious solution, but it is hard to scale. Most teams start out automating a few unit tests, and stop there. However, the real power of test automation kicks in when you automate the bulk of your testing, and leave manual testing only for a small percentage of total tests. Many testing solutions include visual tracking of tests that are ideally suited for automating front-end tests. It’s important to not just stop at unit tests, but to carry automation forward all the way to the front end.
Applications need to perform in a particular manner and teams have to ensure they work the same way in devices with varying operating systems, screen sizes, and models. An application should work the same way, whether it’s a computer or a mobile device. However, it’s unrealistic to replicate all the possible real-world scenarios. An application may perform differently on different devices, based on a number of variables. So, it’s important to not just perform functional testing, but also to consider various other factors that may affect the application.
Emulators and simulators can help test basic tests on mobile devices. But for in-depth testing on mobile, a mobile device lab is required. Rather than build and maintain one on your own, today, it’s possible to rent devices by the minute and run tests on them. It would take a deliberate strategy to decide which tests to run on emulators and which to run on real devices. When done right, these tests can make an app battle-tested and ready for whatever is thrown at it in production.
Various factors contribute to a web page not working the way it’s intended to. So, it’s extremely important that any issue is clearly categorized as either a back end or a front end issue. However, it’s not easy to identify where the problem lies. A page might not load because of a browser issue or simply because the server didn’t respond in time. Therefore, it is important to keep track of various metrics like early interactions and completion of key actions.
The time between a client request and the first bit of the subsequent response to reach the browser is called Time to First Byte (TTFB). Since TTFB usually identifies factors that affect backend, it can be useful in identifying what the issue is by comparing it to the time taken by various key actions. If a short TTFB is followed by a long time for the DOM content to load, then the issue is most definitely a front-end issue. Similarly, logs are very useful in identifying issues and root causes.
Continuous testing is about shifting testing both left and right within the development pipeline. To the left – testing needs to be done early, alongside development. This is made possible by new solutions such as headless testing. This method reduces the size of the instances running the tests and requires running very small, lightweight, and focused tests.
To the right – by implementing advanced testing processes like canary testing. This limits the blast radius of failures, and provides reliable signals about the performance of new features as soon as they are released. A/B testing front-end changes is a great way to incrementally improve an application.
Testing should be continuous and should be performed as early and as frequently as it can be, throughout the application lifecycle.
An application should ideally run the same way on both mobile devices and desktop browsers. However, scripts used to test an application on both types of devices may vary. Also, since PC and mobile applications usually have separate test labs, there can be numerous other variables that can lead to inaccurate results. These inaccurate results can lead developers to look for errors that simply don’t exist.
In order to avoid this challenge, organizations should invest in a cloud-based testing solution that can help developers maintain consistency among various testing environments. Some of these solutions also offer a single testing script to test applications on desktop and mobile devices. Having a mobile testing solution like Sauce Performance Testing that tightly integrates mobile and web is essential for doing great frontend testing.
Front-end performance testing isn’t an easy process. However, making sure it is part of your application development life cycle is extremely important. Performance testing shouldn’t just be a step, it must be an iterative process that keeps on finding new challenges and helps develop a flawless application.
Twain Taylor is a Fixate IO Contributor and began his career at Google, where, among other things, he was involved in technical support for the AdWords team. His work involved reviewing stack traces, and resolving issues affecting both customers and the Support team, and handling escalations. Later, he built branded social media applications, and automation scripts to help startups better manage their marketing operations. Today, as a technology journalist he helps IT magazines, and startups change the way teams build and ship applications.