diff --git a/docs/tutorial.rst b/docs/tutorial.rst
--- a/docs/tutorial.rst
+++ b/docs/tutorial.rst
@@ -164,6 +164,10 @@
 looks much simpler when we look at the actual implementations of the two
 new-style indexing listers we currently have…
 
+An important aspect for making a new lister is its testing. To enable tox on 
+your new lister, you need add your lister in the main conftest.py 
+(swh/lister/core/tests/conftest.py)
+
 This is the entire source code for the BitBucket repository lister::
 
     # Copyright (C) 2017 the Software Heritage developers