Fixed #29711 -- Added a system check for uniquness of admin actions' __name__.

AUTHORS

@@ -686,6 +686,7 @@ answer newbie questions, and generally made Django that much better:
     Preston Holmes <preston@ptone.com>
     Preston Timmons <prestontimmons@gmail.com>
     Priyansh Saxena <askpriyansh@gmail.com>
+    Przemysław Buczkowski <przemub@przemub.pl>
     Przemysław Suliga <http://suligap.net>
     Rachel Tobin <rmtobin@me.com>
     Rachel Willmer <http://www.willmer.com/kb/>

django/contrib/admin/checks.py

@@ -606,6 +606,7 @@ class ModelAdminChecks(BaseModelAdminChecks):
             *self._check_search_fields(admin_obj),
             *self._check_date_hierarchy(admin_obj),
             *self._check_action_permission_methods(admin_obj),
+            *self._check_actions_uniqueness(admin_obj),
         ]
 
     def _check_save_as(self, obj):
@@ -944,6 +945,18 @@ class ModelAdminChecks(BaseModelAdminChecks):
                     )
         return errors
 
+    def _check_actions_uniqueness(self, obj):
+        """Check that every action has a unique __name__."""
+        names = [name for _, name, _ in obj._get_base_actions()]
+        if len(names) != len(set(names)):
+            return [checks.Error(
+                '__name__ attributes of actions defined in %s must be '
+                'unique.' % obj.__class__,
+                obj=obj.__class__,
+                id='admin.E130',
+            )]
+        return []
+
 
 class InlineModelAdminChecks(BaseModelAdminChecks):
 

docs/ref/checks.txt

@@ -593,6 +593,8 @@ with the admin site:
   ``DateTimeField``.
 * **admin.E129**: ``<modeladmin>`` must define a ``has_<foo>_permission()``
   method for the ``<action>`` action.
+* **admin.E130**: ``__name__`` attributes of actions defined in
+  ``<modeladmin>`` must be unique.
 
 ``InlineModelAdmin``
 ~~~~~~~~~~~~~~~~~~~~

tests/modeladmin/test_checks.py

@@ -1309,3 +1309,30 @@ class ActionsCheckTests(CheckTestCase):
             'custom_permission_action action.',
             id='admin.E129',
         )
+
+    def test_actions_not_unique(self):
+        def action(modeladmin, request, queryset):
+            pass
+
+        class BandAdmin(ModelAdmin):
+            actions = (action, action)
+
+        self.assertIsInvalid(
+            BandAdmin, Band,
+            "__name__ attributes of actions defined in "
+            "<class 'modeladmin.test_checks.ActionsCheckTests."
+            "test_actions_not_unique.<locals>.BandAdmin'> must be unique.",
+            id='admin.E130',
+        )
+
+    def test_actions_unique(self):
+        def action1(modeladmin, request, queryset):
+            pass
+
+        def action2(modeladmin, request, queryset):
+            pass
+
+        class BandAdmin(ModelAdmin):
+            actions = (action1, action2)
+
+        self.assertIsValid(BandAdmin, Band)