Front End Testing: A Complete Conceptual Overview

What's visible on the screen is the only thing that matters to end users. A firm needs to check how…

By Testim,

What’s visible on the screen is the only thing that matters to end users. A firm needs to check how a site looks and functions before it goes live. To ensure an impeccable graphical user interface (GUI), front end testing is a must.

In this post, we’re going to understand what front end testing is, its types, importance, and other details. We’ll also cover how it differs from back end testing as well as challenges that are unique to front end testing. In short, I’ll provide a complete conceptual overview of front end testing.

What Is Front End Testing?

The front end is the client-side section of a program. We can say that it involves everything visible while using an application. Every web application has a three-tier architecture. It includes clients, servers, and information systems or resources. The presentation layer comprises the client. Front end testers test this layer. They perform GUI testing and test usability and how a site or application works.

For example, suppose you’re testing a shopping application. Front end testers check whether the look and feel of the website are aligned with the client’s requirements. Also, they check if the required features like adding an item to the shopping cart or menu click events are working properly. Front end testing covers a wide array of testing strategies. We shall discuss this in the next sections. But before diving in, we’ll take a look at how front end testing is different from back end testing.

How Front End and Back End Testing Are Different

We already know from the previous section what front end testing deals with. Now, let’s discuss back end testing.

The back end of an application comprises the database and server-side layer of a three-tier architecture. In other words, the functionality and business logic that make a front end application work are what make up the back end.

Back end testing doesn’t involve the application’s user interface (UI). It mostly checks whether the database stores the right data entered using the UI. Also, if anywhere some data is visible on the UI, back end testers check whether the database queries send the correct data. Let’s dig deep into how back end and front end testing are different.


Front end testers should have knowledge about the client’s requirements. Not only that, experience in automation frameworks will help a front end tester in their job. On the other hand, back end testers must have knowledge about database and SQL queries.

Stuff That Needs Testing

Front end testers should check whether the app’s GUI is error-free. Also, they must check each and every element, like buttons, labels, or drop-down behavior.

Back end testing involves database usage. Testers may or may not use GUI. They must check whether there is any data loss, corruption, or deadlock.


Some important front end testing tools are Grunt, Karma, Mocha, and many others. Popular back end testing tools include Turbo Data, Data Generator, or other API testing tools.

Why Front End Testing Is Needed

So, now that we’re clear about what front end testing is and how it’s different from back end testing, let’s discuss why it’s needed.

End users don’t have that much of an idea regarding how back end stuff works. They only notice when there’s some issue with the application’s UI. Every company wants to thrive. This is possible only if the company provides a consistent customer experience. For instance, an app should provide accurate interaction. It should be fast and run without error, no matter which device or browser is used. This is where front end testing comes into play. Testers perform testing on multiple devices as well as browsers. They declare an app to be error-free only when it satisfies all the testing criteria.

Now, let’s talk about coding. W3C has introduced new criteria for usability and accessibility. Your HTML code must follow certain standards, and your website should be accessible to all, especially people with disabilities. Accessibility testing is a mandatory segment of front end testing. In other words, it’s a must to execute before deploying a website.

Apart from that, the Internet of Things (IoT) has taken app development to a whole new level. With the widespread use of interconnected apps on your smartwatch, smartphone, and smart TV, front end testing is needed to check the behavior of an app over multitier architecture.

Now that we’re clear about why it’s needed, let’s discuss the various types of front end testing.

Types of Front End Testing

Developers are responsible for the consistency and stability of a product. But they can’t accomplish it without testers. Front end testing covers a variety of strategies. It involves some practices that have been prevalent in back end development for years. A testing strategy needs to be compatible with your codebase and testing team. To know the best fit, you must know the types of front end testing. Let’s take a look.

Unit Testing

Every bit of the code should function well independently. A unit refers to the smallest part of a software that is testable. Unit testing is the lowest-level testing among the different testing types. Here, testers test individual components of a software or application. There are one or more inputs with a single output in most cases. Unit testing ensures that individual code sets work according to expectations before building a massive feature. It includes calculations and input validations.

Acceptance Testing

In acceptance testing, testers test a system for acceptability. They evaluate the compliance of a system with business requirements. After that, they test whether the product is acceptable for delivery. For instance, if you’re building a Lego house, you’ll check whether each piece is perfect. That comes under unit testing, which we already discussed in the previous section. The next step is to ensure whether all the instructions have been followed. For that, you need to check after the completion of each stage of the Lego building. Acceptance tests scan the running application. They ensure the proper functioning of user flows, user inputs, and designated actions.

Visual Regression Testing

Whenever some new change is pushed in an application, there’s a slight chance that a preexisting feature may break. That’s where regression testing comes in handy. Visual regression testing is another form of regression testing that’s related to UI. It involves capturing UI screenshots and comparing them with previous screenshots. The previous screenshots are captured from the live site or the baseline. Visual regression testing is unique to the front end. Testers use image comparison tools to detect differences between the two shots. If you’re building something new, save this testing process for last.

Accessibility Testing

As I noted earlier, accessibility testing is to ensure that everyone can access an application. This includes users over a certain age and those with hearing and visual disabilities. Accessibility testing mostly involves checking whether your app is compatible with devices like a screen reader.

Performance Testing

The performance of a site or an application is of prime importance in the technical culture. Performance testing determines the stability, responsiveness, and speed of a product. Also, it examines how a device fares under certain conditions. There are plenty of tools available for performance testing. Most of them are plug-and-play. However, some tools also provide an option for customizing the running of tests.

End-to-End Testing

The application flow should be smooth from the beginning to the end. End-to-end testing ensures that the app behaves according to expectations throughout its running. It also maintains data integrity between systems and between its components. Besides this, end-to-end testing also identifies system dependencies and enables testers to fix any system or setup-related issues.

Integration Testing

Integration testing combines different units and tests them as a group. Generally, single units function well. But they might not interact smoothly after integration. A drop-down list of your site may stop working after it has been integrated into the navigation bar, for example. But don’t worry, integration testing exposes all kinds of bugs that occur after merging codes. Test stubs and test drivers enable smooth integration testing.

Cross-Browser Compatibility Testing

Finally, we’ll discuss the most important type of front end testing: cross-browser compatibility testing. It focuses on enabling users to have the same experience on different browsers. Functioning available on one browser should be available on others too. It also ensures that an application works correctly on different OSes, devices, and browser combinations.

How to Create a Front End Testing Plan

A front end testing plan helps determine the project needs. It also helps in fulfilling those needs step by step. Let’s take a look at how you can create a front end testing plan.

Decide the Budget

In front end testing, you’ll be allotting roles and using tools. Therefore, it’s important to decide the budget beforehand. Even if you’re on a tight budget, ensure the highest quality you’re able to within that budget. For instance, suppose your application needs cross-browser testing. You can save the cost of purchasing and configuring multiple devices, browsers, or operating systems by using a cloud-based cross-browser testing platform.

Decide the Tools

Once you’ve decided on the budget, it’s time to make a list of all the tools you’ll be using. Sometimes, a single tool performs multiple functions. But there are many tasks involved in front end testing. So, you can also use specific tools for different tasks. Deciding which tools to use in advance will help speed up the process.

Set a Timeline

An agile framework can sometimes result in a narrow time window. You need to cover many aspects of front end testing. Therefore, time can be a major constraint. Thus, it’s important to set a timeline before you start testing.

Decide the Scope of a Project

Different ISP plans offer different browsers and OSes. You need to know what your audience is using. Knowing what devices users use is also helpful. Having clarity on the project scope helps cut costs. It also aids in reducing development time.

Popular Front End Testing Tools

Now, we know the importance of front end testing. We’ve also explored how to create a testing plan. But to fully implement a front end testing plan, testers use a combination of different front end testing tools.

Types of Testing Tools

Different testing tools carry out various functions. On that note, let’s check out the types of testing tools.

Test Launchers

You can launch your test in the Node.js or browser with test launchers. Test launchers use CLI or UI with user configuration. But you can also manually open the browser to achieve this. Some test launchers include Karma, Jest, Jasmine, TestCafe, etc.

Structure Providers

Structure providers help in arranging test files. Mocha, Jest, Cucumber, Jasmine, and TestCafe are some tools you can use.

Assertion Functions

It’s important to check whether test returns are aligned to expectations. Some assertion function tools include Chai, Jest, Jasmine, Unexpected, and TestCafe.

Display Test Progress

Another mandatory job for a tester is to check the progress of a test to take further action. Thus, testers use tools to generate and display test results and progress. They include Mocha, Jest, TestCafe, Jasmine, and Karma.

Mocks and Stubs

Sometimes, to catch the side effects of certain tests, it’s important to isolate some parts. For that, testers use mocks, stubs, and a combination of tools. They include Sinon, Enzyme, Jest, Jasmine, and Test Double.

Snapshot Comparison

Snapshot comparison is a must to check the proper implementation of changes. Testers have to compare the snapshots of data structures and different components. Jest and Ava are some tools for this purpose. You can also check Testim’s solution for automated snapshot comparison.

Code Coverage

Each test covers a portion of the code. Generating code coverage reports determines how much code tests cover. Parasoft, Jtest, and Cobertura are a few such tools.

Browser Controllers

For functional tests, simulating user actions is possible by browser controllers. Testers use a combination of different testing tools. They include TestCafe, Nightwatch, Phantom, Nightmare, and Puppeteer (see Testim’s free recorder for Puppeteer).

Visual Regression

Visual regression tools compare a website to its previous version. They also use various image comparison techniques and tools. Some of them include Applitools, Percy, Wraith, and WebdriverCSS.

Front End Testing Challenges and How to Deal With Them

All caught up with the A to Z of front end testing basics? The story doesn’t end here. Every job, whether development or testing, comes with some challenges. Front end testing is no exception. Here, we shall take a look at some common challenges and how to deal with them.

Are You Using Automation for the First Time?

Front end testing, especially cross-browser and regression testing, demands automation. Is your team going to work on a large-scale web app with multiple pages and features? You must be considering whether to implement automation or not. What if your team is using automation for the first time? They may face difficulties regarding setup and writing reusable test cases. If you push them all of a sudden from manual to automation, testing may be time-consuming. In the worst case, your team may not complete testing before the deadline.

To prevent this, start preparing before the project begins. Train your team on automation frameworks that you’re going to use. Additionally, while the development team is doing their work, ask the testing team to write test cases. Resolve all setup-related issues before the development team completes their work.

Emulating the Real World

An even bigger challenge is testers cannot guess how a real user will behave while using the application. Testers face a hard time predicting scenarios related to how a user is going to use a page or feature. While writing the test cases, it’s common to forget cases like if the user logs out and clicks the back button.

Include usability testing as a mandatory phase. This type of testing provides a direct result that shows how a real user will use your site. Set up environments for hallway testing or remote usability testing. Ask your colleagues or other team members to use the application. Check whether there is any user behavior that your team missed out on. Also, focus on performance testing. It’ll show how your application behaves when a large number of users work on it all at once. Performance testing will assure you that your application is ready to handle any sudden rush or a large count of internet traffic.

Agile and Regression

Agile gives a great deal of flexibility to the client. After the delivery of each sprint, the client can check the app and ask for any changes. They can ask your team to add a certain feature or remove a feature that they don’t like. With frequent code changes, the risk of regression bugs increases.

Ask your team to carry out regression testing after the developer addresses a change request. Consider using visual regression tools or snapshot comparing tools. These tools will enable the testing team to easily find any regression bugs, thus reducing the chance of regression bugs during deployment.

Is It Front End or Back End?

An even bigger problem arises when a tester assigns a defect to a developer. Your team may raise a bug, such as if a certain cell in a table is displaying the wrong data. The blame game begins once they assign the bug. The front end person may say that it’s a back end issue. The code is unable to fetch correct data from the database. The back end person may say that code is correct. But the front end code has incorrect data mapping.

For preventing issues like this, encourage your team to follow the best practices. Let them think and work like an agile team. In agile, testers need to be aware of certain development features. Back end and front end developers also need to be aware of each other’s work. If a tester assigns a defect to the wrong person by mistake, that person should do some groundwork on the bug, find the root cause, and ask the appropriate person to fix it.

Wrapping It Up

In today’s era, the internet is at everyone’s fingertips. Even the most subtle errors can affect your company’s reputation. Once a user notices flaws, it spreads like wildfire. Undoubtedly, this makes front end testing even more vital. Do you wish to be the target for online trolls? Of course not! Remember, customers don’t easily forgive. If they observe a slight delay or lag in your website or application, they won’t think twice before switching to another application that serves the same purpose. Your competitors are just a click away! To avoid that, prioritize front end testing in your application’s test cycle. Thus, you’ll ensure the utmost customer satisfaction.

This post was written by Arnab Roy Chowdhury. Arnab is a UI developer by profession and a blogging enthusiast. He has strong expertise in the latest UI/UX trends, project methodologies, testing, and scripting.