One of the best tools for this is PestPHP which is testing framework with focus on simplicity, readability and expressiveness. It is useful because it prevents you from making silly mistakes that could break your code. It's also easy to install and use, so you don't have to worry about any complicated setup process.

PHPstan is a static analysis tool for PHP. It can find and fix common problems in your code, making it easier to write maintainable code. It can also improve the quality of your unit tests by verifying them automatically after each change you make to your codebase. Larastan is a bridge application that uses PHPStan to analyse your PHP code without running it on your web server.

Laravel Pint is an opinionated PHP code style fixer for minimalists. It enforces a consistent code standard across multiple projects. It build on top of PHP Coding Standards Fixer (php-cs-fixer), but extend to support more style and lint rules.

Laravel health check is a tool that checks your Laravel application for common issues. You install it via composer, and it performs the following checks: database connection, file permissions, Blade templating syntax, resource permissions and more.