diff --git a/sentry/tests/test_client.py b/sentry/tests/test_client.py
index 55759a41d..efbcb29d6 100644
--- a/sentry/tests/test_client.py
+++ b/sentry/tests/test_client.py
@@ -36,10 +36,14 @@ class InMemoryTransport(HttpTransport):
 
     def __init__(self, *args, **kwargs):
         self.events = []
+        self.envelopes = []
 
     def capture_event(self, event, *args, **kwargs):
         self.events.append(event)
 
+    def capture_envelope(self, envelope, *args, **kwargs):
+        self.envelopes.append(envelope)
+
     def has_event(self, event_level, event_msg):
         for event in self.events:
             if (