Add explicit test for respecting the error_status responder config

While introducing this on turbo, looks like no specific test was added,
so this at least covers that a bit.

It needs some conditional checks since not all supported Rails +
Responders version work with the customization, so there's one test for
the hardcoded status version too, which can be removed in the future.

test/failure_app_test.rb

@@ -371,6 +371,35 @@ def call_failure(env_params = {})
         end
       end
     end
+
+    # TODO: remove conditional/else when supporting only responders 3.1+
+    if ActionController::Responder.respond_to?(:error_status=)
+      test 'respects the configured responder `error_status` for the status code' do
+        swap Devise.responder, error_status: :unprocessable_entity do
+          env = {
+            "warden.options" => { recall: "devise/sessions#new", attempted_path: "/users/sign_in" },
+            "devise.mapping" => Devise.mappings[:user],
+            "warden" => stub_everything
+          }
+          call_failure(env)
+
+          assert_equal 422, @response.first
+          assert_includes @response.third.body, 'Invalid Email or password.'
+        end
+      end
+    else
+      test 'uses default hardcoded responder `error_status` for the status code since responders version does not support configuring it' do
+        env = {
+          "warden.options" => { recall: "devise/sessions#new", attempted_path: "/users/sign_in" },
+          "devise.mapping" => Devise.mappings[:user],
+          "warden" => stub_everything
+        }
+        call_failure(env)
+
+        assert_equal 200, @response.first
+        assert_includes @response.third.body, 'Invalid Email or password.'
+      end
+    end
   end
 
   context "Lazy loading" do