add abtest

docs/abtesting.md

@@ -9,9 +9,9 @@ The logic of the implement follows this logic:
 * A node can be configured to enable A/B Test. You also define a code to set the name of the test
 * When Murph receives a request, an event is dispatched and contains an `App\Core\Ab\AbTestInterface` object
 * You must create an event subscriber and set variations defined by
-  * a name (a string)
-  * a value (whatever you want)
-  * a percentage chance (optional)
+	- a name (a string)
+	- a value (whatever you want)
+	- a percentage chance (optional)
 * Then a variation is picked and saved in user cookies
 * Finally, you can retrieve the picked variation PHP side and template side
 
@@ -90,3 +90,50 @@ public function foo(AbContainerInterface $testContainer)
     {# ... #}
 {% endif %}
 ```
+
+## Global A/B Test
+
+If you need to perform an A/B test everywhere, you need to create a specific listener:
+
+```
+// src/EventListener/CustomAbListener.php
+
+namespace App\EventListener;
+
+use App\Core\EventListener\AbListener as EventListener;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpKernel\Event\RequestEvent;
+
+class CustomAbListener extends EventListener
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected function supports(Request $request): bool
+    {
+        return true;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function getAbTestCode(): string
+    {
+        return 'my_global_ab_test_code';
+    }
+}
+```
+
+`CustomAbListener` must be registred:
+
+```
+# config/services.yml
+
+services:
+	# ...
+
+    App\EventListener\CustomAbListener;
+        tags:
+            - { name: kernel.event_listener, event: kernel.request }
+            - { name: kernel.event_listener, event: kernel.response }
+```