Issue #2982693 by jhedstrom, borisson_, drunken monkey: Adapted tests to latest Core changes.

Author: jhedstrom

Diff for: CHANGELOG.txt

@@ -1,5 +1,7 @@
 Search API 1.x, dev (xxxx-xx-xx):
 ---------------------------------
+- #2982693 by jhedstrom, borisson_, drunken monkey: Adapted tests to latest
+  Core changes.
 - #2971033 by mErilainen, drunken monkey, borisson_: Added an option for prefix
   matching to the database backend.
 - #2973034 by idebr, drunken monkey: Removed outdated @todo comment.

Diff for: tests/src/Kernel/Index/IndexImportTest.php

@@ -93,6 +93,9 @@ public function testIndexImport() {
     ];
     $sync->write('search_api.index.database_search_index', $import_config);
 
+    // The system.site key is required for import validation.
+    $sync->write('system.site', []);
+
     // Import the test configuration.
     $config_importer = $this->configImporter();
     $this->assertTrue($config_importer->hasUnprocessedConfigurationChanges(), 'Import prepared');