Ruleset: use MsgCollector for "register() method must return an array" error

Includes some new assertions which won't run until the test suite supports PHPUnit 10+ (PHPCS 4.0). These tests belong with this commit though, so adding them now anyway.

Author: jrfnl

src/Ruleset.php

@@ -1460,8 +1460,12 @@ public function populateTokenListeners()
 
             $tokens = $this->sniffs[$sniffClass]->register();
             if (is_array($tokens) === false) {
-                $msg = "ERROR: Sniff $sniffClass register() method must return an array";
-                throw new RuntimeException($msg);
+                $msg = "The sniff $sniffClass register() method must return an array.";
+                $this->msgCache->add($msg, MsgCollector::ERROR);
+
+                // Unregister the sniff.
+                unset($this->sniffs[$sniffClass], $this->sniffCodes[$sniffCode], $this->deprecatedSniffs[$sniffCode]);
+                continue;
             }
 
             $ignorePatterns = [];

tests/Core/Ruleset/PopulateTokenListenersRegisterNoArrayTest.xml

@@ -5,4 +5,6 @@
 
     <rule ref="TestStandard.InvalidSniffs.RegisterNoArray"/>
 
+    <!-- Prevent a "no sniff were registered" error. -->
+    <rule ref="Generic.PHP.BacktickOperator"/>
 </ruleset>

tests/Core/Ruleset/PopulateTokenListenersTest.php

@@ -62,11 +62,16 @@ public function testSniffWhereRegisterDoesNotReturnAnArrayThrowsException()
         $config   = new ConfigDouble(["--standard=$standard"]);
 
         $sniffClass = 'Fixtures\\TestStandard\\Sniffs\\InvalidSniffs\\RegisterNoArraySniff';
-        $message    = "ERROR: Sniff $sniffClass register() method must return an array";
+        $message    = "ERROR: The sniff $sniffClass register() method must return an array.".PHP_EOL.PHP_EOL;
         $this->expectRuntimeExceptionMessage($message);
 
         new Ruleset($config);
 
+        // Verify that the sniff has not been registered/has been unregistered.
+        // These assertions will only take effect for PHPUnit 10+.
+        $this->assertArrayNotHasKey($sniffClass, self::$ruleset->sniffs, "Sniff class $sniffClass is listed in registered sniffs");
+        $this->assertArrayNotHasKey('TestStandard.InvalidSniffs.RegisterNoArray', self::$ruleset->sniffCodes, 'Sniff code is registered');
+
     }//end testSniffWhereRegisterDoesNotReturnAnArrayThrowsException()