diff --git a/channels/backends/database.py b/channels/backends/database.py
index fdc866a..d1514fa 100644
--- a/channels/backends/database.py
+++ b/channels/backends/database.py
@@ -168,3 +168,6 @@ class DatabaseChannelBackend(BaseChannelBackend):
 
     def __str__(self):
         return "%s(alias=%s)" % (self.__class__.__name__, self.connection.alias)
+
+    def flush(self):
+        pass
diff --git a/channels/backends/memory.py b/channels/backends/memory.py
index 1d78363..9fff16c 100644
--- a/channels/backends/memory.py
+++ b/channels/backends/memory.py
@@ -92,3 +92,9 @@ class InMemoryChannelBackend(BaseChannelBackend):
         Unlocks the named channel. Always succeeds.
         """
         locks.discard(channel)
+
+    def flush(self):
+        global queues, groups, locks
+        queues = {}
+        groups = {}
+        locks = set()
diff --git a/channels/backends/redis_py.py b/channels/backends/redis_py.py
index df81a35..f48f799 100644
--- a/channels/backends/redis_py.py
+++ b/channels/backends/redis_py.py
@@ -61,11 +61,6 @@ class RedisChannelBackend(BaseChannelBackend):
         host, port = self.hosts[index]
         return redis.Redis(host=host, port=port)
 
-    @property
-    def connections(self):
-        for i in range(len(self.hosts)):
-            return self.connection(i)
-
     def send(self, channel, message):
         # if channel is no str (=> bytes) convert it
         if not isinstance(channel, str):
@@ -189,3 +184,7 @@ class RedisChannelBackend(BaseChannelBackend):
 
     def __str__(self):
         return "%s(hosts=%s)" % (self.__class__.__name__, self.hosts)
+
+    def flush(self):
+        for i in range(self.ring_size):
+            self.connection(i).flushdb()
diff --git a/channels/tests/test_backends.py b/channels/tests/test_backends.py
index 3d63e0e..c2cbba6 100644
--- a/channels/tests/test_backends.py
+++ b/channels/tests/test_backends.py
@@ -13,6 +13,7 @@ class MemoryBackendTests(TestCase):
 
     def setUp(self):
         self.backend = self.backend_class(routing={})
+        self.backend.flush()
 
     def test_send_recv(self):
         """