diff --git a/src/allmydata/test/web/test_common.py b/src/allmydata/test/web/test_common.py
index b399b77c8..5bc8ce4f0 100644
--- a/src/allmydata/test/web/test_common.py
+++ b/src/allmydata/test/web/test_common.py
@@ -44,6 +44,11 @@ from .common import (
 )
 
 class StaticResource(Resource, object):
+    """
+    ``StaticResource`` is a resource that returns whatever Python object it is
+    given from its render method.  This is useful for testing
+    ``render_exception``\\ 's handling of different render results.
+    """
     def __init__(self, response):
         Resource.__init__(self)
         self._response = response