Add support for reconfiguring handlers in tests

Signed-off-by: Aleksi Häkli <aleksi.hakli@iki.fi>

axes/signals.py

@@ -3,6 +3,7 @@ from logging import getLogger
 from django.contrib.auth.signals import user_logged_in
 from django.contrib.auth.signals import user_logged_out
 from django.contrib.auth.signals import user_login_failed
+from django.core.signals import setting_changed
 from django.db.models.signals import post_save, post_delete
 from django.dispatch import receiver
 from django.dispatch import Signal
@@ -32,14 +33,14 @@ class ProxyHandler:
     implementation = None  # concrete handler that is bootstrapped by the Django application loader
 
     @classmethod
-    def initialize(cls):
+    def initialize(cls, force=False):
         """
         Fetch and initialize concrete handler implementation and memoize it to avoid reinitialization.
 
         This method is re-entrant and can be called multiple times.
         """
 
-        if cls.implementation is None:
+        if force or cls.implementation is None:
             cls.implementation = import_string(settings.AXES_HANDLER)()
 
     @classmethod
@@ -124,3 +125,14 @@ def handle_post_save_access_attempt(*args, **kwargs):
 @receiver(post_delete, sender=AccessAttempt)
 def handle_post_delete_access_attempt(*args, **kwargs):
     ProxyHandler.post_delete_access_attempt(*args, **kwargs)
+
+
+@receiver(setting_changed)
+def handle_setting_changed(sender, setting, value, enter, **kwargs):  # pylint: disable=unused-argument
+    """
+    Reinitialize handler implementation if a relevant setting changes
+    in e.g. application reconfiguration or during testing.
+    """
+
+    if enter and setting == 'AXES_HANDLER':
+        ProxyHandler.initialize(force=enter)

axes/tests/test_handlers.py

@@ -16,6 +16,15 @@ class ProxyHandlerTestCase(TestCase):
         self.user = MagicMock()
         self.instance = MagicMock()
 
+    @patch('axes.signals.import_string', return_value=AxesHandler)
+    def test_setting_changed_signal_triggers_handler_reimport(self, importer):
+        self.assertEqual(0, importer.call_count)
+
+        with self.settings(
+            AXES_HANDLER='axes.handlers.AxesHandler'
+        ):
+            self.assertEqual(1, importer.call_count)
+
     @patch('axes.signals.ProxyHandler.implementation', None)
     @patch('axes.signals.import_string', return_value=AxesHandler)
     def test_initialize(self, importer):