diff --git a/channels/tests/base.py b/channels/tests/base.py
index b42914e..248a837 100644
--- a/channels/tests/base.py
+++ b/channels/tests/base.py
@@ -7,6 +7,7 @@ from functools import wraps
 
 from django.test.testcases import TestCase
 from .. import DEFAULT_CHANNEL_LAYER
+from ..channel import Group
 from ..routing import Router, include
 from ..asgi import channel_layers, ChannelLayerWrapper
 from ..message import Message
@@ -133,6 +134,9 @@ class Client(object):
         if message:
             return message.content
 
+    def join_group(self, group_name):
+        Group(group_name).add(self.reply_channel)
+
 
 class apply_routes(object):
     """