Issue #3325571 by Murz, andypost, smustgrave, catch, larowlan: MemoryStorage fails with "Argument #1 ($array) must be of type array" error on calling function readMultiple()

core/lib/Drupal/Core/Config/MemoryStorage.php

@@ -31,6 +31,7 @@ class MemoryStorage implements StorageInterface {
   public function __construct($collection = StorageInterface::DEFAULT_COLLECTION) {
     $this->collection = $collection;
     $this->config = new \ArrayObject();
+    $this->config[$collection] = [];
   }
 
   /**

core/tests/Drupal/KernelTests/Core/Config/Storage/CachedStorageTest.php

@@ -37,8 +37,6 @@ class CachedStorageTest extends ConfigStorageTestBase {
     $this->fileStorage = new FileStorage($dir);
     $this->storage = new CachedStorage($this->fileStorage, \Drupal::service('cache.config'));
     $this->cache = \Drupal::service('cache_factory')->get('config');
-    // ::listAll() verifications require other configuration data to exist.
-    $this->storage->write('system.performance', []);
   }
 
   /**

core/tests/Drupal/KernelTests/Core/Config/Storage/ConfigStorageTestBase.php

@@ -39,6 +39,9 @@ abstract class ConfigStorageTestBase extends KernelTestBase {
     // Checking whether a non-existing name exists returns FALSE.
     $this->assertFalse($this->storage->exists($name));
 
+    // Checking whether readMultiple() works with empty storage.
+    $this->assertEmpty($this->storage->readMultiple([$name]));
+
     // Reading a non-existing name returns FALSE.
     $data = $this->storage->read($name);
     $this->assertFalse($data);
@@ -59,6 +62,7 @@ abstract class ConfigStorageTestBase extends KernelTestBase {
     $this->assertTrue($result);
 
     // Listing all names returns all.
+    $this->storage->write('system.performance', []);
     $names = $this->storage->listAll();
     $this->assertContains('system.performance', $names);
     $this->assertContains($name, $names);

core/tests/Drupal/KernelTests/Core/Config/Storage/DatabaseStorageTest.php

@@ -20,9 +20,6 @@ class DatabaseStorageTest extends ConfigStorageTestBase {
 
     $this->storage = new DatabaseStorage($this->container->get('database'), 'config');
     $this->invalidStorage = new DatabaseStorage($this->container->get('database'), 'invalid');
-
-    // ::listAll() verifications require other configuration data to exist.
-    $this->storage->write('system.performance', []);
   }
 
   protected function read($name) {

core/tests/Drupal/KernelTests/Core/Config/Storage/ManagedStorageTest.php

@@ -28,8 +28,6 @@ class ManagedStorageTest extends ConfigStorageTestBase implements StorageManager
   protected function setUp(): void {
     parent::setUp();
     $this->storage = new ManagedStorage($this);
-    // ::listAll() verifications require other configuration data to exist.
-    $this->storage->write('system.performance', []);
   }
 
   /**

core/tests/Drupal/KernelTests/Core/Config/Storage/MemoryStorageTest.php

@@ -17,8 +17,6 @@ class MemoryStorageTest extends ConfigStorageTestBase {
   protected function setUp(): void {
     parent::setUp();
     $this->storage = new MemoryStorage();
-    // ::listAll() verifications require other configuration data to exist.
-    $this->storage->write('system.performance', []);
   }
 
   /**

core/tests/Drupal/KernelTests/Core/Config/Storage/StorageReplaceDataWrapperTest.php

@@ -18,9 +18,6 @@ class StorageReplaceDataWrapperTest extends ConfigStorageTestBase {
   protected function setUp(): void {
     parent::setUp();
     $this->storage = new StorageReplaceDataWrapper($this->container->get('config.storage'));
-    // ::listAll() verifications require other configuration data to exist.
-    $this->storage->write('system.performance', []);
-    $this->storage->replaceData('system.performance', ['foo' => 'bar']);
   }
 
   /**