Ruleset: remove support for sniffs nor implementing Sniff interface

Previously truly invalid sniffs would already be ignored/rejected, but sniffs which didn't implement the interface, but did implement the required methods would still be accepted.

Now, both will be rejected.

Includes removing the `RegisterSniffsRejectsInvalidSniffTest` class as these tests are now redundant (covered via the `RegisterSniffsMissingInterfaceTest` class).

This commit executes step 4 to address issue 694..

Closes 694

Related to 6

Author: jrfnl

src/Ruleset.php

@@ -1418,24 +1418,9 @@ public function registerSniffs($files, $restrictions, $exclusions)
                 $message  = 'All sniffs must implement the PHP_CodeSniffer\\Sniffs\\Sniff interface.'.PHP_EOL;
                 $message .= "Interface not implemented for sniff $className.".PHP_EOL;
                 $message .= 'Contact the sniff author to fix the sniff.';
-                $this->msgCache->add($message, MessageCollector::DEPRECATED);
-
-                // Skip classes which don't implement the register() or process() methods.
-                if (method_exists($className, 'register') === false
-                    || method_exists($className, 'process') === false
-                ) {
-                    $errorMsg = 'Sniff class %s is missing required method %s().';
-                    if (method_exists($className, 'register') === false) {
-                        $this->msgCache->add(sprintf($errorMsg, $className, 'register'), MessageCollector::ERROR);
-                    }
-
-                    if (method_exists($className, 'process') === false) {
-                        $this->msgCache->add(sprintf($errorMsg, $className, 'process'), MessageCollector::ERROR);
-                    }
-
-                    continue;
-                }
-            }//end if
+                $this->msgCache->add($message, MessageCollector::ERROR);
+                continue;
+            }
 
             $listeners[$className] = $className;
 

tests/Core/Ruleset/Fixtures/TestStandard/Sniffs/InvalidSniffError/NoImplementsNoProcessSniff.php

@@ -6,7 +6,6 @@
     <rule ref="TestStandard">
         <exclude name="TestStandard.SupportedTokenizers"/>
         <exclude name="TestStandard.InvalidSniffs"/>
-        <exclude name="TestStandard.InvalidSniffError"/>
         <exclude name="TestStandard.MissingInterface.InvalidImplementsWithoutImplement"/>
     </rule>
 

tests/Core/Ruleset/Fixtures/TestStandard/Sniffs/InvalidSniffError/NoImplementsNoRegisterOrProcessSniff.php

@@ -1,6 +1,6 @@
 <?php
 /**
- * Tests deprecation of support for sniffs not implementing the PHPCS `Sniff` interface.
+ * Tests removed support for sniffs not implementing the PHPCS `Sniff` interface.
  *
  * @author    Juliette Reinders Folmer <[email protected]>
  * @copyright 2025 PHPCSStandards and contributors
@@ -11,14 +11,14 @@
 
 use PHP_CodeSniffer\Ruleset;
 use PHP_CodeSniffer\Tests\ConfigDouble;
-use PHPUnit\Framework\TestCase;
+use PHP_CodeSniffer\Tests\Core\Ruleset\AbstractRulesetTestCase;
 
 /**
- * Tests deprecation of support for sniffs not implementing the PHPCS `Sniff` interface.
+ * Tests removed support for sniffs not implementing the PHPCS `Sniff` interface.
  *
  * @covers \PHP_CodeSniffer\Ruleset::registerSniffs
  */
-final class RegisterSniffsMissingInterfaceTest extends TestCase
+final class RegisterSniffsMissingInterfaceTest extends AbstractRulesetTestCase
 {
 
 
@@ -41,25 +41,25 @@ public function testNoNoticesForSniffsImplementingInterface()
 
 
     /**
-     * Test that a deprecation notice is shown if a sniff doesn't implement the Sniff interface.
+     * Test that an error is shown if a sniff doesn't implement the Sniff interface.
      *
      * @return void
      */
-    public function testDeprecationNoticeWhenSniffDoesntImplementInterface()
+    public function testErrorWhenSniffDoesntImplementInterface()
     {
         // Set up the ruleset.
         $standard = __DIR__.'/RegisterSniffsMissingInterfaceInvalidTest.xml';
         $config   = new ConfigDouble(["--standard=$standard"]);
 
-        $expected  = 'DEPRECATED: All sniffs must implement the PHP_CodeSniffer\\Sniffs\\Sniff interface.'.PHP_EOL;
+        $expected  = 'ERROR: All sniffs must implement the PHP_CodeSniffer\\Sniffs\\Sniff interface.'.PHP_EOL;
         $expected .= 'Interface not implemented for sniff Fixtures\\TestStandard\\Sniffs\\MissingInterface\\InvalidImplementsWithoutImplementSniff.'.PHP_EOL;
         $expected .= 'Contact the sniff author to fix the sniff.'.PHP_EOL.PHP_EOL;
 
-        $this->expectOutputString($expected);
+        $this->expectRuntimeExceptionMessage($expected);
 
         new Ruleset($config);
 
-    }//end testDeprecationNoticeWhenSniffDoesntImplementInterface()
+    }//end testErrorWhenSniffDoesntImplementInterface()
 
 
 }//end class