How to add a dev dependency in the require section of your composer.json file?

In the composer.json file, development dependencies (dev dependencies) are added to the require-dev section. This allows you to separate libraries needed only for development and testing from those required in production.

Example of adding a dev dependency:

{
  "require-dev": {
    "phpunit/phpunit": "^9.5"
  }
}

To add a dependency via the command line, you can use:

composer require --dev phpunit/phpunit

This will automatically add the package to the require-dev section of your composer.json.