Issue #3224239 by bircher, rpayanm, smustgrave: StorageComparer does not work when storages are not in the default collection

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

@@ -90,6 +90,13 @@ class StorageComparer implements StorageComparerInterface {
    *   Storage object used to write configuration.
    */
   public function __construct(StorageInterface $source_storage, StorageInterface $target_storage) {
+    if ($source_storage->getCollectionName() !== StorageInterface::DEFAULT_COLLECTION) {
+      $source_storage = $source_storage->createCollection(StorageInterface::DEFAULT_COLLECTION);
+    }
+    if ($target_storage->getCollectionName() !== StorageInterface::DEFAULT_COLLECTION) {
+      $target_storage = $target_storage->createCollection(StorageInterface::DEFAULT_COLLECTION);
+    }
+
     // Wrap the storages in a static cache so that multiple reads of the same
     // raw configuration object are not costly.
     $this->sourceCacheStorage = new MemoryBackend();

core/tests/Drupal/Tests/Core/Config/StorageComparerTest.php

@@ -3,7 +3,9 @@
 namespace Drupal\Tests\Core\Config;
 
 use Drupal\Component\Uuid\Php;
+use Drupal\Core\Config\MemoryStorage;
 use Drupal\Core\Config\StorageComparer;
+use Drupal\Core\Config\StorageInterface;
 use Drupal\Tests\UnitTestCase;
 
 /**
@@ -42,6 +44,14 @@ class StorageComparerTest extends UnitTestCase {
   protected function setUp(): void {
     $this->sourceStorage = $this->createMock('Drupal\Core\Config\StorageInterface');
     $this->targetStorage = $this->createMock('Drupal\Core\Config\StorageInterface');
+
+    $this->sourceStorage->expects($this->atLeastOnce())
+      ->method('getCollectionName')
+      ->will($this->returnValue(StorageInterface::DEFAULT_COLLECTION));
+    $this->targetStorage->expects($this->atLeastOnce())
+      ->method('getCollectionName')
+      ->will($this->returnValue(StorageInterface::DEFAULT_COLLECTION));
+
     $this->storageComparer = new StorageComparer($this->sourceStorage, $this->targetStorage);
   }
 
@@ -241,4 +251,56 @@ class StorageComparerTest extends UnitTestCase {
     $this->assertEmpty($this->storageComparer->getChangelist('delete'));
   }
 
+  /**
+   * @covers ::createChangelist
+   */
+  public function testDifferentCollections() {
+    $source = new MemoryStorage();
+    $target = new MemoryStorage();
+
+    $this->generateRandomData($source, 's');
+    $this->generateRandomData($target, 't');
+
+    // Use random collections for source and target.
+    $collections = $source->getAllCollectionNames();
+    $source = $source->createCollection($collections[array_rand($collections)]);
+    $collections = $target->getAllCollectionNames();
+    $target = $target->createCollection($collections[array_rand($collections)]);
+
+    $comparer = new StorageComparer($source, $target);
+    $comparer->createChangelist();
+
+    foreach (array_merge([StorageInterface::DEFAULT_COLLECTION], $source->getAllCollectionNames(), $target->getAllCollectionNames()) as $collection) {
+      $expected = [
+        'create' => $source->createCollection($collection)->listAll(),
+        'update' => [],
+        'delete' => $target->createCollection($collection)->listAll(),
+        'rename' => [],
+      ];
+
+      $this->assertEqualsCanonicalizing($expected, $comparer->getChangelist(NULL, $collection));
+    }
+  }
+
+  /**
+   * Generate random data in a config storage.
+   *
+   * @param \Drupal\Core\Config\StorageInterface $storage
+   *   The storage to populate with random data.
+   * @param string $prefix
+   *   The prefix for random names to make sure they are unique.
+   */
+  protected function generateRandomData(StorageInterface $storage, string $prefix = '') {
+    $generator = $this->getRandomGenerator();
+    for ($i = 0; $i < rand(2, 10); $i++) {
+      $storage->write($prefix . $this->randomMachineName(), (array) $generator->object());
+    }
+    for ($i = 0; $i < rand(1, 5); $i++) {
+      $collection = $storage->createCollection($prefix . $this->randomMachineName());
+      for ($i = 0; $i < rand(2, 10); $i++) {
+        $collection->write($prefix . $this->randomMachineName(), (array) $generator->object());
+      }
+    }
+  }
+
 }