1 files changed, 65 insertions, 0 deletions
diff --git a/actionpack/test/controller/parameters/dup_test.rb b/actionpack/test/controller/parameters/dup_test.rb
new file mode 100644
index 0000000000..fb707a1354
--- /dev/null
+++ b/actionpack/test/controller/parameters/dup_test.rb
@@ -0,0 +1,65 @@
+require "abstract_unit"
+require "action_controller/metal/strong_parameters"
+require "active_support/core_ext/object/deep_dup"
+
+class ParametersDupTest < ActiveSupport::TestCase
+  setup do
+    ActionController::Parameters.permit_all_parameters = false
+
+    @params = ActionController::Parameters.new(
+      person: {
+        age: "32",
+        name: {
+          first: "David",
+          last: "Heinemeier Hansson"
+        },
+        addresses: [{ city: "Chicago", state: "Illinois" }]
+      }
+    )
+  end
+
+  test "a duplicate maintains the original's permitted status" do
+    @params.permit!
+    dupped_params = @params.dup
+    assert dupped_params.permitted?
+  end
+
+  test "a duplicate maintains the original's parameters" do
+    @params.permit!
+    dupped_params = @params.dup
+    assert_equal @params.to_h, dupped_params.to_h
+  end
+
+  test "changes to a duplicate's parameters do not affect the original" do
+    dupped_params = @params.dup
+    dupped_params.delete(:person)
+    assert_not_equal @params, dupped_params
+  end
+
+  test "changes to a duplicate's permitted status do not affect the original" do
+    dupped_params = @params.dup
+    dupped_params.permit!
+    assert_not_equal @params, dupped_params
+  end
+
+  test "deep_dup content" do
+    dupped_params = @params.deep_dup
+    dupped_params[:person][:age] = "45"
+    dupped_params[:person][:addresses].clear
+
+    assert_not_equal @params[:person][:age], dupped_params[:person][:age]
+    assert_not_equal @params[:person][:addresses], dupped_params[:person][:addresses]
+  end
+
+  test "deep_dup @permitted" do
+    dupped_params = @params.deep_dup
+    dupped_params.permit!
+
+    assert_not @params.permitted?
+  end
+
+  test "deep_dup @permitted is being copied" do
+    @params.permit!
+    assert @params.deep_dup.permitted?
+  end
+end