Snapshot testing is a popular type of regression testing that a lot of development teams are unaware has untapped potential when it comes to accessibility. The AccessibilitySnapshot library offers a way to bring accessibility into your automated regression suite. By treating the accessibility hierarchy as a testable artifact, developers can catch issues early and maintain a consistent, inclusive experience for all users.
What Is Snapshot Testing?
Snapshot testing is a regression‑testing technique that compares the current output of a component to a previously approved “snapshot.” In traditional iOS development, this often means capturing a visual rendering of a view and ensuring it hasn’t changed unexpectedly. It’s a powerful way to detect unintended UI shifts, layout regressions, or styling inconsistencies.
Accessibility snapshot testing applies the same philosophy, but focuses on semantics over pixels. The snapshot will include labels, traits, hints, element order, grouping, and the overall accessibility hierarchy. These items directly impact how assistive technology interacts with your mobile application, so treating them as part of your regression suite is a natural extension of of snapshot testing.
Running an Accessibility Snapshot
The Accessibility Snapshot Library from the folks at CashApp makes it straightforward to incorporate accessibility snapshots into your test suite. The library makes use of the already established 'SnapshotTesting' Framework, and allows you to add in accessibility assertions with ease.
//Function to create hosting controller
func createHost<Content: View>(_ view: Content) -> UIHostingController<Content> {
let hostingController = UIHostingController(rootView: view)
hostingController.view.frame = UIScreen.main.bounds
return hostingController
}
//Snapshot test for home screen
func testHomeScreenAccessibility() {
let home = HomeView()
assertSnapshot(matching: createHost(home), as: .accessibilityImage)
}
In this test case we create a function to create a UIHostingController and then a test case to make a snapshot of the home screen of our application. When this test case runs, we will get an accessibility snapshot that looks like the following:
The output allows testers to be able to see the accessibility hierarchy of their application and check for semantic structure, grouping, or proper trait issues without ever using a screen reader!
Why Accessibility Snapshot Testing Matters
- Reliable Regression Detection
Accessibility regressions are often subtle. A renamed label, a missing trait, or a restructured view hierarchy may not be visually obvious, yet they can dramatically affect how a screen is navigated with assistive technology. Snapshot testing catches these issues early—before they reach users.
- Clear, Readable Output
One of the strengths of the AccessibilitySnapshot library is the clarity of its output. Instead of trying to use the screen reader light on the accessibility inspector or manually inspecting elements, developers and testers a structured representation of the accessibility tree. This makes debugging faster and helps teams build a shared understanding of accessible UI design.
Summary
Accessibility snapshot testing brings a powerful new dimension to automated testing in iOS. With tools like Accessibility Snapshot, teams can validate the structure and semantics of their UI with ease. The result is a more stable, predictable, and inclusive experience for users who rely on assistive technologies.
To see a full working example, please visit iOS-Automated-Accessibility-Library
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