Composer: add PHPCSExtra

Add PHPCSExtra as a new dependency. PHPCSExtra is an external standard for PHP_CodeSniffer and is also a requirement for WPCS 3.0.0.

The reason to add it as a direct requirement for YoastCS is that we'll not only be using sniffs from PHPCSExtra via WPCS, but also want to use additional sniffs which PHPCSExtra has to offer, which makes it not just a requirement of WPCS, but also a requirement of YoastCS.

Ref: https://github.com/PHPCSStandards/PHPCSExtra

.github/workflows/basics.yml

@@ -54,6 +54,7 @@ jobs:
         run: >
           composer require --no-update --no-scripts --no-interaction
           squizlabs/php_codesniffer:"dev-master"
+          phpcsstandards/phpcsextra:"dev-develop"
 
       # Install dependencies and handle caching in one go.
       # @link https://github.com/marketplace/actions/install-composer-dependencies

README.md

@@ -66,6 +66,7 @@ The `Yoast` standard for PHP_CodeSniffer is comprised of the following:
 * The `WordPress` ruleset from the [WordPress Coding Standards](https://github.com/WordPress/WordPress-Coding-Standards) implementing the official [WordPress PHP Coding Standards](https://make.wordpress.org/core/handbook/coding-standards/php/), with some [select exclusions](https://github.com/Yoast/yoastcs/blob/develop/Yoast/ruleset.xml#L29-L75).
 * The [`PHPCompatibilityWP`](https://github.com/PHPCompatibility/PHPCompatibilityWP) ruleset which checks code for PHP cross-version compatibility while preventing false positives for functionality polyfilled within WordPress.
 * Select additional sniffs taken from [`PHP_CodeSniffer`](https://github.com/squizlabs/PHP_CodeSniffer).
+* Select additional sniffs taken from [`PHPCSExtra`](https://github.com/PHPCSStandards/PHPCSExtra).
 * A number of custom Yoast specific sniffs.
 
 Files within version management and dependency related directories, such as the Composer `vendor` directory, are excluded from the scans by default.

composer.json

@@ -29,6 +29,7 @@
 		"php-parallel-lint/php-console-highlighter": "^1.0.0",
 		"php-parallel-lint/php-parallel-lint": "^1.3.2",
 		"phpcompatibility/phpcompatibility-wp": "^2.1.4",
+		"phpcsstandards/phpcsextra": "^1.1.2",
 		"squizlabs/php_codesniffer": "^3.7.2",
 		"wp-coding-standards/wpcs": "^2.3.0"
 	},