Ticket #24618: 24618.2.patch

src/wp-includes/user-functions.php

@@ -1182 +1182 @@
  */
 function validate_username( $username ) {
         $sanitized = sanitize_user( $username, true );
-        $valid = ( $sanitized == $username );
+        $valid = ( $sanitized == $username && ! empty( $sanitized ) );
         /**
          * Filter whether the provided username is valid or not.
          *

tests/phpunit/tests/user.php

@@ -596 +596 @@
                         if ( ! defined( 'WP_IMPORTING' ) ) {
                                 $this->assertWPError( $return );
                         }
+        }
+
+        /**
+         * @ticket 24618
+         */
+        function test_validate_username() {
+
+                $this->assertTrue( validate_username( 'testusername' ) );
+                $this->assertTrue( validate_username( 'JohnDoe' ) );
+                $this->assertTrue( validate_username( 'test@test.com' ) );
+                $this->assertFalse( validate_username( '' ) );
+                $this->assertFalse( validate_username( '@#&99sd' ) );
+
+        }
                 }
         }