Fixes #1733 - Error on short prefixes

Author: NielsdeBlaauw

WordPress/Sniffs/NamingConventions/PrefixAllGlobalsSniff.php

@@ -33,6 +33,17 @@ class PrefixAllGlobalsSniff extends AbstractFunctionParameterSniff {
 	 */
 	const ERROR_MSG = '%s by a theme/plugin should start with the theme/plugin prefix. Found: "%s".';
 
+	/**
+	 * Minimal number of characters the prefix needs in order to be valid.
+	 *
+	 * @since 2.2.0
+	 *
+	 * @link https://github.com/WordPress/WordPress-Coding-Standards/issues/1733 Issue 1733.
+	 *
+	 * @var int
+	 */
+	const MIN_PREFIX_LENGTH = 3;
+
 	/**
 	 * Target prefixes.
 	 *
@@ -914,6 +925,16 @@ private function validate_prefixes() {
 				continue;
 			}
 
+			if ( function_exists( 'iconv_strlen' ) && iconv_strlen( $prefix, $this->phpcsFile->config->encoding ) < self::MIN_PREFIX_LENGTH ) {
+				$this->phpcsFile->addError(
+					'The "%s" prefix is too short. Short prefixes are not unique enough and may cause name collisions with other code.',
+					0,
+					'ShortPrefixPassed',
+					array( $prefix )
+				);
+				continue;
+			}
+
 			// Validate the prefix against characters allowed for function, class, constant names etc.
 			if ( preg_match( '`^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff\\\\]*$`', $prefix ) !== 1 ) {
 				$this->phpcsFile->addWarning(

WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.1.inc

@@ -425,3 +425,28 @@ define(
 );
 
 // phpcs:set WordPress.NamingConventions.PrefixAllGlobals prefixes[]
+
+/*
+ * Bad: Issue https://github.com/WordPress/WordPress-Coding-Standards/issues/1733.
+ * 
+ * Short prefixes are not allowed. The errors are triggered
+ * on LINE 1 for the unit-test, because it's the phpcs:set command that is
+ * wrong, not the implementing code.
+ */
+// phpcs:set WordPress.NamingConventions.PrefixAllGlobals prefixes[] a
+function a_do_something(){}
+
+// phpcs:set WordPress.NamingConventions.PrefixAllGlobals prefixes[] aa
+function aa_do_something(){}
+
+// The following line mimicks an empty prefix value.
+// phpcs:set WordPress.NamingConventions.PrefixAllGlobals prefixes[] ,
+function aa_do_something(){}
+
+// phpcs:set WordPress.NamingConventions.PrefixAllGlobals prefixes[] 😊
+function 😊_do_something(){}
+
+// phpcs:set WordPress.NamingConventions.PrefixAllGlobals prefixes[] 😊😊
+function 😊😊_do_something(){}
+
+// phpcs:set WordPress.NamingConventions.PrefixAllGlobals prefixes[]

WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.php

@@ -32,7 +32,7 @@ public function getErrorList( $testFile = 'PrefixAllGlobalsUnitTest.1.inc' ) {
 		switch ( $testFile ) {
 			case 'PrefixAllGlobalsUnitTest.1.inc':
 				return array(
-					1   => 2, // 1 x error for blacklisted prefix passed.
+					1   => 8, // 2 x error for blacklisted prefix passed. 4 x error for short prefixes. 2 x no prefix.
 					10  => 1,
 					18  => 1,
 					21  => 1,