1 files changed, 30 insertions, 0 deletions
diff --git a/actionpack/test/controller/parameters/always_permitted_parameters_test.rb b/actionpack/test/controller/parameters/always_permitted_parameters_test.rb
new file mode 100644
index 0000000000..974612fb7b
--- /dev/null
+++ b/actionpack/test/controller/parameters/always_permitted_parameters_test.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require "abstract_unit"
+require "action_controller/metal/strong_parameters"
+
+class AlwaysPermittedParametersTest < ActiveSupport::TestCase
+  def setup
+    ActionController::Parameters.action_on_unpermitted_parameters = :raise
+    ActionController::Parameters.always_permitted_parameters = %w( controller action format )
+  end
+
+  def teardown
+    ActionController::Parameters.action_on_unpermitted_parameters = false
+    ActionController::Parameters.always_permitted_parameters = %w( controller action )
+  end
+
+  test "returns super on missing constant other than NEVER_UNPERMITTED_PARAMS" do
+    ActionController::Parameters.superclass.stub :const_missing, "super" do
+      assert_equal "super", ActionController::Parameters::NON_EXISTING_CONSTANT
+    end
+  end
+
+  test "allows both explicitly listed and always-permitted parameters" do
+    params = ActionController::Parameters.new(
+      book: { pages: 65 },
+      format: "json")
+    permitted = params.permit book: [:pages]
+    assert_predicate permitted, :permitted?
+  end
+end