Why You Shouldn’t Skimp on Both Functional and Visual UI Testing

  July 11, 2023

There are many components to a successful web testing strategy, but one of the most often overlooked is the importance of visual UI testing in addition to functional testing.

Most teams will focus on one over the other, but to truly catch as many bugs as possible, you’ll need to incorporate both. First, you need to understand what the difference is and why they’re both needed.

Functional Testing

Let’s start by defining what functional testing is. Functional testing examines how the software actually works in relation to the given requirements.

For example, a homepage on an e-commerce web application might have a menu button. If clicked, it’s expected to drop down with different options.

Functional testing is executed on tests of all sizes, from unit tests to end-to-end cases. It’s critical for making sure that user flows work as intended and are consistent with the product manager’s vision.

So for the same example with the menu button, you may also check that clicking a drop-down option takes you to the correct page. You can continue to perform a functional test case (that includes adding an item to your cart and checking out) to ensure each of those actions work one after another and allow the user to make a purchase.

To dive a little deeper, functional tests are basically actions and validations -- the tester or tool performs an action with an expected validation. Which either works or doesn’t work.

Most of the time, when we talk about functional testing, we’re referring to automated testing where we’re getting a pass or fail test result. When thinking about cross-browser and device testing, functional testing should be included after deciding which browsers and devices to test in order to make sure those tests pass across different configurations.

If you’re in development, design, or QA, this information isn’t news to you. However, differentiating between functional and visual testing, and understanding when each is needed, will inform a more intelligent testing strategy.

Visual Testing

It’s clearly important to test the functional elements of your application. But some teams make the mistake of functional efficiency being the bulk of their testing with no regard for visual validation.

Visual testing requires the tester to consider how the application looks in addition to how it works. Often times, the UI of an application can pass a functional test while visual defects go under the radar.

Source: Baymard Institute

This becomes extremely important as we look at responsive design and consider the myriad of devices, browsers, and operating systems. If an application is not built to be responsive, design elements may suffer on different screen sizes, compromising the user experience.

Again, this can go unnoticed if just functional testing is performed.

Visual bugs can be annoying to users, but they can go beyond inconvenience to be more severe. In fact, visual inconsistencies affect the user journey in a way that makes it difficult or even impossible to complete their intended actions even though the test is functionally proficient.

You can see the spectrum of severity when it comes to visual bugs in the following images from the Baymard Institute. In the screenshot of Amazon’s website, the text overlay has not rendered properly and is hard to read. In the example with the form field, visual issues make it difficult to fill out.

The issue may be that teams don’t have the time or capacity to do visual testing, or that they don’t prioritize it, but there are many organizations that are simply unaware that it should be an integral part of their strategy.

Automating Functional and Visual UI Tests

As mentioned, functional UI testing is most often done with a test automation tool, such as Selenium or Record & Replay, (in TestComplete). It runs your test in multiple browsers and gives you a pass or fail. The results tell you if and where the application is working as intended.

Visual testing, on the other hand, has classically been more of a manual task. Afterall, a “fail” is how it looks to the human eye.

However, this doesn’t mean you should have to do visual testing all by hand and manually compare your website in different browsers. So how do you speed up visual testing?

A tool like VisualTest makes it easy to add automated visual regression testing to your suite.

Test Visually in a Fraction of the Time

By adding just a single code snippet to your automation script, you can do away with extensive lines of functional test script and catch visual bugs using AI. The benefit of a tool like this means you aren’t manually combing through screenshots in the hopes of catching defects.

VisualTest is also integrated with BitBar, so that once you run your visual tests, you can automatically check them across hundreds of real devices and browsers.

This way your functional and visual tests are verified against the latest, most up-to-date browsers and devices your customers are using.

Don’t Skimp on the Necessities

Visual testing isn’t as optional as it once was. By implementing these automation practices and incorporating visual testing into your existing strategy, your team can achieve more testing coverage without wasting any time. You will release faster and at higher quality.

In summary:

  • Make sure your application works correctly and looks great.
  • Visual bugs could prevent your users from completing a crucial task.
  • Automate your functional and visual tests to release faster and with more confidence.
  • Ensure the best user experience by testing across different browsers and devices.

Try for free!

Check out VisualTest today by starting a trial or simply signing up for a free plan! You’ll see just how easy it is to automate your visual tests and begin delivering higher quality releases.