[TASK] Provide encryptionKey in unit tests

Since TYPO3 12.4.11 and 11.5.35 the encryptionKey is not initialized
in the default configuration, thus some unit tests will fail.

This commit ensures an encryptionKey is set for the unit tests.

Resolves: TYPO3-Solr#3958

Tests/Unit/Domain/Variants/IdBuilderTest.php

@@ -32,29 +32,14 @@
  */
 class IdBuilderTest extends SetUpUnitTestCase
 {
-    protected string $oldEncryptionKey;
-
-    protected function setUp(): void
-    {
-        $this->oldEncryptionKey = $GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey'];
-        $GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey'] = 'testkey';
-        parent::setUp();
-    }
-
-    protected function tearDown(): void
-    {
-        $GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey'] = $this->oldEncryptionKey;
-        parent::tearDown();
-    }
-
     /**
      * @test
      */
     public function canBuildVariantId(): void
     {
         $build = new IdBuilder(new NoopEventDispatcher());
         $variantId = $build->buildFromTypeAndUid('pages', 4711, [], $this->createMock(Site::class), new Document());
-        self::assertSame('e99b3552a0451f1a2e7aca4ac06ccaba063393de/pages/4711', $variantId);
+        self::assertSame('c523304ea47711019595d2bb352b623d1db40427/pages/4711', $variantId);
     }
 
     /**

Tests/Unit/SetUpUnitTestCase.php

@@ -27,13 +27,25 @@
 abstract class SetUpUnitTestCase extends UnitTestCase
 {
     protected bool $resetSingletonInstances = true;
+    protected ?string $originalEncryptionKey;
 
     protected function setUp(): void
     {
         date_default_timezone_set('Europe/Berlin');
+        $this->originalEncryptionKey = $GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey'] ?? null;
+        $GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey'] = 'solr-tests-secret-encryption-key';
         parent::setUp();
     }
 
+    protected function tearDown(): void
+    {
+        unset($GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey']);
+        if ($this->originalEncryptionKey !== null) {
+            $GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey'] = $this->originalEncryptionKey;
+        }
+        parent::tearDown();
+    }
+
     /**
      * Returns the absolute root path to the fixtures.
      *