add handler with exatractor

src/handler.rs

@@ -155,6 +155,14 @@ impl Reply {
             _ => None,
         }
     }
+
+    #[cfg(test)]
+    pub(crate) fn into_future(self) -> Box<Future<Item=HttpResponse, Error=Error>> {
+        match self.0 {
+            ReplyItem::Future(fut) => fut,
+            _ => panic!(),
+        }
+    }
 }
 
 impl Responder for Reply {