Introducing coding standards validation.

vendor/wp-coding-standards/wpcs/WordPress/Sniffs/DB/RestrictedClassesSniff.php

@@ -0,0 +1,60 @@
+<?php
+/**
+ * WordPress Coding Standard.
+ *
+ * @package WPCS\WordPressCodingStandards
+ * @link    https://github.com/WordPress-Coding-Standards/WordPress-Coding-Standards
+ * @license https://opensource.org/licenses/MIT MIT
+ */
+
+namespace WordPress\Sniffs\DB;
+
+use WordPress\AbstractClassRestrictionsSniff;
+
+/**
+ * Verifies that no database related PHP classes are used.
+ *
+ * "Avoid touching the database directly. If there is a defined function that can get
+ *  the data you need, use it. Database abstraction (using functions instead of queries)
+ *  helps keep your code forward-compatible and, in cases where results are cached in memory,
+ *  it can be many times faster."
+ *
+ * @link    https://make.wordpress.org/core/handbook/best-practices/coding-standards/php/#database-queries
+ *
+ * @package WPCS\WordPressCodingStandards
+ *
+ * @since   0.10.0
+ * @since   0.13.0 Class name changed: this class is now namespaced.
+ */
+class RestrictedClassesSniff extends AbstractClassRestrictionsSniff {
+
+	/**
+	 * Groups of classes to restrict.
+	 *
+	 * Example: groups => array(
+	 *  'lambda' => array(
+	 *      'type'    => 'error' | 'warning',
+	 *      'message' => 'Avoid direct calls to the database.',
+	 *      'classes' => array( 'PDO', '\Namespace\Classname' ),
+	 *  )
+	 * )
+	 *
+	 * @return array
+	 */
+	public function getGroups() {
+		return array(
+
+			'mysql' => array(
+				'type'    => 'error',
+				'message' => 'Accessing the database directly should be avoided. Please use the $wpdb object and associated functions instead. Found: %s.',
+				'classes' => array(
+					'mysqli',
+					'PDO',
+					'PDOStatement',
+				),
+			),
+
+		);
+	}
+
+}