diff --git a/doc/source/developer/testing.rst b/doc/source/developer/testing.rst
index 4a813d0..057ab7e 100644
--- a/doc/source/developer/testing.rst
+++ b/doc/source/developer/testing.rst
@@ -9,6 +9,8 @@
 access to a number of attributes useful for manipulating or inspecting
 the environment being simulated in the test:
 
+.. autofunction:: tests.base.simple_layout
+
 .. autoclass:: tests.base.ZuulTestCase
    :members: