Issue #3209931 by daffie, longwave: The service...

Issue #3209931 by daffie, longwave: The service "cache_tags.invalidator.checksum" and the service "cache.backend.database" should be backend_overridable

core/core.services.yml

@@ -198,6 +198,7 @@ services:
     arguments: ['@database']
     tags:
       - { name: cache_tags_invalidator}
+      - { name: backend_overridable }
   cache.backend.chainedfast:
     class: Drupal\Core\Cache\ChainedFastBackendFactory
     arguments: ['@settings']
@@ -206,6 +207,8 @@ services:
   cache.backend.database:
     class: Drupal\Core\Cache\DatabaseBackendFactory
     arguments: ['@database', '@cache_tags.invalidator.checksum', '@settings']
+    tags:
+      - { name: backend_overridable }
   cache.backend.apcu:
     class: Drupal\Core\Cache\ApcuBackendFactory
     arguments: ['%app.root%', '%site.path%', '@cache_tags.invalidator.checksum']

core/tests/Drupal/KernelTests/Core/Cache/DatabaseBackendTest.php

@@ -103,4 +103,20 @@ protected function getNumRows() {
     return (int) $query->execute()->fetchField();
   }
 
+  /**
+   * Test that the service "cache_tags.invalidator.checksum" is backend overridable.
+   */
+  public function testCacheTagsInvalidatorChecksumIsBackendOverridable() {
+    $definition = $this->container->getDefinition('cache_tags.invalidator.checksum');
+    $this->assertTrue($definition->hasTag('backend_overridable'));
+  }
+
+  /**
+   * Test that the service "cache.backend.database" is backend overridable.
+   */
+  public function testCacheBackendDatabaseIsBackendOverridable() {
+    $definition = $this->container->getDefinition('cache.backend.database');
+    $this->assertTrue($definition->hasTag('backend_overridable'));
+  }
+
 }