test(handler): stub CrlRevocationChecker::validate() in AEngineHandlerTest

The mock returned null by default, causing AEngineHandler to access
$crlDetails['status'] on a null value and trigger a PHP warning.
Stubbing validate() to return ['status' => CrlValidationStatus::VALID]
fulfils the contract and silences the warning.

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

tests/php/Unit/Handler/CertificateEngine/AEngineHandlerTest.php

@@ -10,6 +10,7 @@
  */
 
 use OCA\Libresign\AppInfo\Application;
+use OCA\Libresign\Enum\CrlValidationStatus;
 use OCA\Libresign\Handler\CertificateEngine\OpenSslHandler;
 use OCA\Libresign\Service\CaIdentifierService;
 use OCA\Libresign\Service\CertificatePolicyService;
@@ -22,6 +23,7 @@
 use OCP\ITempManager;
 use OCP\IURLGenerator;
 use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\MockObject\MockObject;
 use Psr\Log\LoggerInterface;
 
 final class AEngineHandlerTest extends \OCA\Libresign\Tests\Unit\TestCase {
@@ -35,7 +37,7 @@ final class AEngineHandlerTest extends \OCA\Libresign\Tests\Unit\TestCase {
 	private CaIdentifierService $caIdentifierService;
 	private LoggerInterface $logger;
 	private SubjectAlternativeNameService $subjectAlternativeNameService;
-	private CrlRevocationChecker $crlRevocationChecker;
+	private CrlRevocationChecker&MockObject $crlRevocationChecker;
 
 	public function setUp(): void {
 		$this->config = \OCP\Server::get(IConfig::class);
@@ -52,6 +54,7 @@ public function setUp(): void {
 		$this->logger = \OCP\Server::get(LoggerInterface::class);
 		$this->subjectAlternativeNameService = \OCP\Server::get(SubjectAlternativeNameService::class);
 		$this->crlRevocationChecker = $this->createMock(CrlRevocationChecker::class);
+		$this->crlRevocationChecker->method('validate')->willReturn(['status' => CrlValidationStatus::VALID]);
 	}
 
 	private function getInstance(): OpenSslHandler {