      def receiver(self, **kwargs):
          self.received.append(kwargs)
  
      def test_invalid_sender_model_name(self):
          msg = "Specified sender must either be a model or a model name of the 'app_label.ModelName' form."
          with self.assertRaisesMessage(ValueError, msg):
              signals.post_init.connect(self.receiver, sender='invalid')
  
      def test_already_loaded_model(self):
          signals.post_init.connect(
 
</s> remove     @isolate_apps('signals')
    def test_not_loaded_model(self):
 </s> add     @isolate_apps('signals', kwarg_name='apps')
    def test_not_loaded_model(self, apps): </s> remove             self.receiver, sender='signals.Created', weak=False
 </s> add             self.receiver, sender='signals.Created', weak=False, apps=apps
        msg = "Invalid model reference 'invalid'. String model references must be of the form 'app_label.ModelName'."
      def receiver(self, **kwargs):
          self.received.append(kwargs)
  
      def test_invalid_sender_model_name(self):
        msg = "Invalid model reference 'invalid'. String model references must be of the form 'app_label.ModelName'."
          with self.assertRaisesMessage(ValueError, msg):
              signals.post_init.connect(self.receiver, sender='invalid')
  
      def test_already_loaded_model(self):
          signals.post_init.connect(
keep keep keep keep replace keep keep keep keep keep
 Fixed #26421 -- Refactored ModelSignal to use Apps.lazy_model_operation() 
tests/signals/tests.py