Issue #2143011 by damiankloip: Add a CacheFactoryInterface.

core/lib/Drupal/Core/Cache/CacheFactory.php

@@ -14,7 +14,7 @@ use Drupal\Component\Utility\Settings;
 use Symfony\Component\DependencyInjection\ContainerAware;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 
-class CacheFactory extends ContainerAware {
+class CacheFactory extends ContainerAware implements CacheFactoryInterface {
 
   /**
    * The settings array.

core/lib/Drupal/Core/Cache/CacheFactoryInterface.php

@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Cache\CacheFactoryInterface.
+ */
+
+namespace Drupal\Core\Cache;
+
+/**
+ * An interface defining cache factory classes.
+ */
+interface CacheFactoryInterface {
+
+  /**
+   * Gets a cache backend class for a given cache bin.
+   *
+   * @param string $bin
+   *   The cache bin for which a cache backend object should be returned.
+   *
+   * @return \Drupal\Core\Cache\CacheBackendInterface
+   *   The cache backend object associated with the specified bin.
+   */
+  public function get($bin);
+
+}

core/lib/Drupal/Core/Cache/DatabaseBackendFactory.php

@@ -9,7 +9,7 @@ namespace Drupal\Core\Cache;
 
 use Drupal\Core\Database\Connection;
 
-class DatabaseBackendFactory {
+class DatabaseBackendFactory implements CacheFactoryInterface {
 
   /**
    * The database connection.

core/lib/Drupal/Core/Cache/MemoryBackendFactory.php

@@ -7,16 +7,10 @@
 
 namespace Drupal\Core\Cache;
 
-class MemoryBackendFactory {
+class MemoryBackendFactory implements CacheFactoryInterface {
 
   /**
-   * Gets MemoryBackend for the specified cache bin.
+   * {@inheritdoc}
-   *
-   * @param $bin
-   *   The cache bin for which the object is created.
-   *
-   * @return \Drupal\Core\Cache\MemoryBackend
-   *   The cache backend object for the specified cache bin.
    */
   function get($bin) {
     return new MemoryBackend($bin);