Visual Testing for Mobile Apps- Why Is It Important?

4 min readMar 8


There are many kinds of testing and quality assurance methods for growing apps today. You have a variety of methodologies to select from, including manual testing, functional testing, end-to-end testing, and unit testing. Each testing method adds to the project’s value and raises the standard of the work. Some of those methods are also misunderstood or not properly used.

The testing of the user interface itself causes the most confusion. Teams typically test more than just the UI, such as how the UI components behave. This isn’t necessarily a terrible thing, but it doesn’t offer a workable alternative to the issue of UI testing. Fortunately, assistance is provided by so-called visual testing, the best method for producing UI elements of the greatest caliber. We focused on the advantages of visual testing and how they may be used in real-world mobile applications.

Which Visual Problems Are Not Detected Functionally?

Developers should visually test their apps for a purpose, especially if they conduct automated functional testing. When doing a functional test, testers confirm that the action and behavior (output) are related (input). Generally speaking, this works out nicely when done automatically.

For instance, during the checkout process while buying a t-shirt. The test involves placing the t-shirt in the shopping cart, entering payment information, and clicking the “Buy Now” button.

But visually, the location of the “Buy Now” button is unclear. It could have moved off the screen considerably or been blocked by anything else on the page. Since the test may “click” the button no matter where it is located, this cannot be identified in a functional test. This test would pass since it does not evaluate the UI’s visual elements. By doing a visual test to look for any visual regressions, situations like these may be swiftly fixed and avoided.

Although an application may render correctly on one browser, this does not guarantee it will do so on another. Cross-browser testing is an excellent idea because there are increasing combinations of operating systems, viewport sizes, and browsers. This will help you identify any visual variances.

How Does Visual Testing Work?

Visual tests create, examine, and contrast browser snapshots to determine whether any pixels have changed. Visual diffs are the names for these pixel differences.

QAs require the following for visual testing for mobile applications:

A test runner to create and run tests

A platform for browser automation that replicates user behaviors

Code written by developers imitates user functions. They insert orders to take screenshots at the right places in the code. An initial set of screenshots is taken when the test code is run to serve as a baseline for future comparison of any modifications.

After establishing the baseline, the QA executes the test code in the background. A screenshot is taken each time a change is seen. The baseline image relating to that specific piece of the code and the program is then compared to each screenshot. If there are discrepancies between the photos, the test is deemed unsuccessful.

The test code automatically generates a report when it has finished running. A QA examines each image identified as having altered from its baseline. After the test has been run, some testing systems produce reports emphasizing the variations between the baseline and final photos.

If defects are to blame for these picture disparities, developers can repair them and rerun the test to see if the modifications were successful. Developers will need to analyze the snapshot and update baseline photos to execute visual tests in the future if further UI modifications bring on variances.

Testers do not need to repeat any network queries, run test setups, add fictitious data, or modify the user interface (UI) to an acceptable state. Additionally, Percy has several features designed to make the most of each visual exam. This includes stopping GIFs and CSS animations, stabilizing dynamic data, and concealing or altering UI elements — all of which reduce false positives.

Benefits of visual testing

The major advantages of adopting visual testing methods are quicker bug detection and regression avoidance. The procedure requires designers to keep the user interface (UI) of greater quality across various devices. The designers may want to reconsider how they approach designs for devices with various screen sizes or resolutions if they become aware of UI problems. It takes a lot of time to locate edge situations linked to certain device views manually, but visual tests make this possible. In a pinch, visual testing’s primary advantages are:

Quick bug detection

Regression reduction

Increased quality of the code and UI

Control of views on different devices

Code reduction

Effective feedback for designers

Low entry barrier

Fast implementation

Lower workload for testers



Before a software release is released into production, visual testing should be included in the arsenal of tests and performed on it. It is crucial that instances in which functionalities are missing, the text is not visible, or the application’s layout is distorted or obstructed are evaluated for each software version, given the variety of devices and resolutions your website or mobile application must support. An efficient way to deal with these problems is through visual testing.

Press Release Distributed by The Express Wire

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