Document weak lagging vendors mode

greg0ire · greg0ire · commit 6301a75f94bd · 2017-11-16T17:51:46.000+01:00
Refs symfony/symfony#24867
diff --git a/components/phpunit_bridge.rst b/components/phpunit_bridge.rst
@@ -171,6 +171,15 @@ the ``vendors`` directory will make the test suite fail, while deprecations
 triggered from a library inside it will not, giving you the best of both
 worlds.
 
+When working on a project, you might be more interested in the
+``weak_lagging_vendors``, which is a bit more strict. Let's say you want to fix
+deprecations as soon as they appear. A problem many people experience is that
+some dependencies they have tend to lag behind their own dependencies, meaning
+they do not fix deprecations as soon as possible, which means there is nothing
+you can do to fix that (apart from a pull request on the lagging vendor). This
+mode allows you to ignore those deprecations, allowing you to notice when your
+code is using deprecated APIs, and to keep up with the changes.
+
 Disabling the Deprecation Helper
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
