README.md in gds-sso-11.0.0 vs README.md in gds-sso-11.1.0

@@ -72,5 +72,15 @@
     bundle exec ./script/make_oauth_work_in_dev
 
 Once that's done, set an environment variable when you run your app. e.g.:
 
     GDS_SSO_STRATEGY=real bundle exec rails s
+
+## Running the tests
+
+Run the tests with:
+
+    bundle exec rake
+
+By default, the tests use the master of [Signon](https://github.com/alphagov/signonotron2) for running integration tests. If you want to use a branch (or commit, or tag), you can run it like this:
+
+    SIGNON_COMMITISH=my_branch_name bundle exec rake