Add flush method to storages

libraries/joomla/cache/storage.php

@@ -253,6 +253,18 @@ public function clean($group, $mode = null)
 		return true;
 	}
 
+	/**
+	 * Flush all existing items in storage.
+	 *
+	 * @return  boolean
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function flush()
+	{
+		return true;
+	}
+
 	/**
 	 * Garbage collect expired cache data
 	 *

libraries/joomla/cache/storage/memcache.php

@@ -278,6 +278,23 @@ public function clean($group, $mode = null)
 		return true;
 	}
 
+	/**
+	 * Flush all existing items in storage.
+	 *
+	 * @return  boolean
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function flush()
+	{
+		if (!$this->lockindex())
+		{
+			return false;
+		}
+
+		return static::$_db->flush();
+	}
+
 	/**
 	 * Test to see if the storage handler is available.
 	 *

libraries/joomla/cache/storage/memcached.php

@@ -294,6 +294,23 @@ public function clean($group, $mode = null)
 		return true;
 	}
 
+	/**
+	 * Flush all existing items in storage.
+	 *
+	 * @return  boolean
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function flush()
+	{
+		if (!$this->lockindex())
+		{
+			return false;
+		}
+
+		return static::$_db->flush();
+	}
+
 	/**
 	 * Test to see if the storage handler is available.
 	 *

tests/unit/core/case/cache.php

@@ -62,7 +62,9 @@ protected function tearDown()
 
 		if ($this->handler instanceof JCacheStorage)
 		{
+			// Deprecated, temporary have to stay because flush method is not implemented in all storages.
 			$this->handler->clean($this->group);
+			$this->handler->flush();
 		}
 
 		parent::tearDown();