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Front End Testing: A Beginner’s Guide

Shreya Bose, Technical Content Writer at BrowserStack -

Table of Contents

What is Front End Testing?

To start with, the front end is any part of a software application that a user interacts with. Essentially, it is all aspects of software visible to clients. This usually includes GUI elements such as menus, buttons, forms – anything end-users can see when navigating the application. It can also include aspects like page load speed – factors contributing to overall user experience.

Front End Testing validates that said GUI elements are functioning as expected. For example, it checks if input fields accept the right characters, if forms are being submitted only after the required fields are filled, if navigation is easy enough, if the page is loading fast enough, etc.

The goal of Front End Testing is to test functionalities and verify that a website or app’s presentation layer is bug or error-free. This has to be done after every single update to ensure recent changes have not degraded any aspect of the UI.

Why do you need Front End Testing?

  • Identifying Performance Issues: Web applications possess three functional layers – clients, servers, resources (or information systems). Front End Testing handles the client layer AKA the part of software presented to the client.

It isn’t uncommon for devs to focus on the server and resources layers, as they are the foundation on which the software is built. However, Front End testing is essential for QA teams to analyze software behavior from end users’ perspectives. It is necessary to detect client-side performance issues that may sabotage critical workflows and contribute to undesirable user experiences.

  • Verifying cross-browser and cross-device functionality: A significant aspect of Front End testing is verifying website and app behavior on multiple browsers, browser versions, and devices (mobile and desktop). This includes not just features but responsiveness on screens of various sizes and resolutions.

Regular software updates, browser updates, and new device releases can lead to gaps in compatibility, which is where Front End testing comes in. A website or app must be tested on multiple browser-device-OS combinations to ensure it behaves as expected on each one.

The only way to ensure this is to perform comprehensive cross browser testing across real browsers and devices. Testers need to check how the software renders and operates in real user conditions, for which they need to test on multiple unique browser-device-OS combinations.

To do so, QAs must run Front End tests on real browsers, devices, and operating systems.  The software will have to render perfectly on each device, browser, and browser version, considering their technical variances and idiosyncrasies. Given that there are at least 63,000 possible browser-platform-device combinations in popular usage, QA teams need access to a massive on-premise device lab (constantly updated with newer devices) to perform satisfactory cross browser compatibility testing.

Not every organization has the finances or the human resources to set up and maintain such a lab, and they don’t have to. They can use BrowserStack, a cloud-based testing platform offering access to a real device cloud of 2000+ real browsers and devices. Be it manual testing or automated Selenium testing, testers can utilize BrowserStack’s infrastructure to get 100% accurate results in real-world circumstances.

  • Verifying integration of Third-Party Services: With Software as a Service platform becoming almost commonplace, most applications leverage third-party integrations to offer better services and heightened user experiences. However, faulty integrations are often a major cause of software malfunction or, at least, unsatisfactory user journeys of some kind.

To prevent some damaged user experiences, Front End tests are mandatory. All third-party integrations must be tested (across browsers, devices, and platforms) to ensure that they function seamlessly and within accepted standards.

Types of Front End Testing

  • Unit Testing

A unit test verifies the functionality of the smallest possible module or “unit” of an application, independently from other modules. In this case, testers and/or developers isolate the smallest application components, check their behavior and identify defects early on in the development pipeline.

For example, in C#, consider a method as a unit (smallest component to be tested). In this case, the unit test would verify some features of the method in isolation from other methods i.e. the software at large. Unit Tests are usually categorized as state-based and interaction-based testing. The former checks to see if the software is producing expected results under specific conditions. The latter verifies if the software properly calls particular methods to accomplish its purpose.

Learn more about the best practices for Unit Testing.
  • Visual Regression Testing

Regression Testing is used to verify that any system changes do not interfere with existing features and/or code structure. There’s a reason regression tests are part of almost every test suite in software development. It is common for devs to change or add a section of code, and having it unintentionally disrupt something that was previously working just fine.

Visual Regression Testing applies the same logic but confines testing to the visual aspects of the software. In other words, it checks that code changes do not break any aspect of the software’s visual interface. A visual regression test checks what the user will see after any code changes have been executed by comparing screenshots taken before and after code changes. This is why visual regression tests are also sometimes called visual snapshot tests.

Read More: An Introduction to Visual Regression Testing
  • Integration Testing

Integration testing verifies the interface between two software units or modules. It focuses on checking if modules are communicating adequately and exposes any errors between integrated units. Integration tests are essential to analyzing the behavior of systems comprising multiple, connected elements. Unit tests are generally followed by integration tests.

Since most contemporary software depends greatly on numerous microservices working in tandem, integration testing also validates the interaction between these services to ensure smooth inter dependability and functioning. Primarily, integration testing checks that the application interface and API communicate smoothly to exchange data required for optimal performance.

  • Acceptance Testing

Acceptance testing determines if a software system meets all predetermined specifications. It evaluates if the system complies with business, technical, and aesthetic requirements so that business stakeholders and end-users can be satisfied alike.

Acceptance tests are generally divided into – User Acceptance Testing and Business Acceptance Testing. The former checks to ensure that the product is meeting all performance standards from users’ perspective while the latter establishes that the software aligns with business goals and requirements.

  • Cross Browser Testing

As explained above, cross browser testing allows testers to check if a website works as expected when accessed via different browser-device-OS combinations. This applies to different versions of the same browser and assistive tools.

Apps must be tested on different device-OS combinations. Among other things, testing responsive design is a key aspect of cross browser and cross device testing. Testers can use BrowserStack’s free responsive design checker to check their software’s appearance on the latest real devices.

Run Cross Browser Tests on Real Browsers & Devices

Front End Testing Best Practices

  • Start with the testing pyramid: For testers and teams just starting out with Front End testing, it’s a good idea to use the testing pyramid as a blueprint. That means: start running unit tests, then move on to integration testing, and finally, execute end to end testing. Once this structure is in place, it will be relatively easy to achieve reasonably high test coverage.

Dive deeper into the testing pipeline, and add more kinds of tests once the pyramid comes into action. Once unit tests, integration tests, and end-to-end tests are completed, it will be easier to expand the testing scope and include things like acceptance testing, visual testing, etc.

  • Use real browsers and devices: As mentioned previously multiple times, real browsers and devices are essential to conducting error-free, reliable Front End tests. Don’t bother with emulators and simulators. Go straight to the real thing, save time, effort and get results that can be counted on.
  • Decide the Front End elements to be prioritized: Front End testing requires the analysis and verification of hundreds, sometimes thousands of UI elements as well as functional elements. The former includes things like formatting, CSS, text, graphics, while the latter comprises forms, links, buttons, etc.

For effective testing, these elements must be prioritized to decide what gets tested first. For example, it makes sense to test page load time, basic text, images, and important functions (adding to cart, payment) first, and then move on to graphics and pop-ups. Check that all elements are visible and responsive, and then move on to verifying graphics and layout.

  • Choose the right Front End testing tools: Outside of providing real browsers and devices for test execution (and this is a mandatory feature), the ideal Front End testing tool should offer ways to make the process as seamless as possible.

BrowserStack, for example, offers a range of debugging options, and pre-installed developer tools that testers can quickly access to identify and resolve bugs. It also offers integrations with a range of necessary tools spanning automation frameworks, CI/CD, build and playback, record and deploy, and much, much more.

In other words, find a tool that provides a comprehensive set of resources covering every step of the testing pipeline. The tool should be able to let QAs run tests, identify bugs, file and forward bugs to other team members, debug, and deploy.

Front End Testing ensures that users get the best possible experience when they access a website or app. Needless to say, it is a key part of any testing pipeline. Consequently, testers need to be meticulous in their planning, execution, and implementation of Front End testing.

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