The webhook committed. The sender never received the acknowledgement. Now it retries.

That is different from a handler that failed and rolled back. If you test only exceptions inside the handler, you can miss the successful-commit/uncertain-delivery boundary.

If your only test throws inside the handler, it may never exercise the successful-commit/uncertain-delivery boundary. A recovery test should state both the delivery observation and the business invariant.

I maintain Laravel FailureLab , an MIT, test-only package for named fault injection and bounded sequential replay. Its public runner is in-process, not a distributed network simulator.

Install in the test application

composer require --dev mykholy/laravel-failurelab:^1.2

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Use PHP 8.3+, Laravel 12/13, APP_ENV=testing and disposable storage.…