Consider a production Laravel application that needs to use Testability. How should the developer approach the requirement, and what should be checked before releasing it?

Consider a production Laravel application that needs to use Testability. How should the developer approach the requirement, and what should be checked before releasing it? Assume the system receives real users, real data and concurrent requests. The correct approach is to identify where testability belongs, define its inputs and outputs, protect the boundary with validation and authorization where applicable, consider database and performance implications, and add automated tests for the expected behavior. Concept-specific reasoning: Dependency injection makes it easier to substitute fakes or mocks during automated tests. A useful implementation pattern is: interface PaymentGateway {} class CheckoutService { public function __construct( private PaymentGateway $gateway ) {} }