How to catch invisible UI bugs before they reach users
A bug that passes every automated test can still crash when users interact with your app. That’s exactly what happened recently in a Laravel admin panel built with Flux, where a wrong icon name slipped through all feature tests—only to fail at runtime. The solution? A static test that reads Blade templates and validates every icon reference before the code ever runs.
The hidden flaw in runtime assumptions
Feature tests typically assert HTTP status codes or basic UI elements, but they often miss subtle rendering issues. In this case, Flux delegates icon resolution through <flux:delegate-component>, which throws an error for an invalid icon name. The problem? Flux ships Heroicons by default, not Lucide, so developers might accidentally use a Lucide icon name that Flux doesn’t recognize. The crash only surfaced in a fully booted environment—exactly where automated tests don’t usually look.
A static check that catches what tests miss
Instead of relying on runtime validation, a static test scans Blade views for all icon references, including those hidden in dynamic expressions like icon="{{ $cond ? 'eye-slash' : 'eye' }}". It then verifies that each referenced icon exists in Flux’s stub directory. This approach catches mismatches early and provides clear feedback when a test fails, reminding developers that Flux uses Heroicons, not Lucide.
The test runs against the source of truth—the actual icon stubs in the vendor directory—so it stays accurate even as the icon set evolves. It also flags issues like Pro-only icons that might not be available in all environments. With this guardrail in place, a production crash becomes a CI failure, where it belongs.
Source: DEV Community. AI-assisted editorial synthesis — TechnoExpress.