1 files changed, 70 insertions, 0 deletions
diff --git a/actionpack/test/controller/parameters/log_on_unpermitted_params_test.rb b/actionpack/test/controller/parameters/log_on_unpermitted_params_test.rb
new file mode 100644
index 0000000000..fc9229ca1d
--- /dev/null
+++ b/actionpack/test/controller/parameters/log_on_unpermitted_params_test.rb
@@ -0,0 +1,70 @@
+# frozen_string_literal: true
+
+require "abstract_unit"
+require "action_controller/metal/strong_parameters"
+
+class LogOnUnpermittedParamsTest < ActiveSupport::TestCase
+  def setup
+    ActionController::Parameters.action_on_unpermitted_parameters = :log
+  end
+
+  def teardown
+    ActionController::Parameters.action_on_unpermitted_parameters = false
+  end
+
+  test "logs on unexpected param" do
+    params = ActionController::Parameters.new(
+      book: { pages: 65 },
+      fishing: "Turnips")
+
+    assert_logged("Unpermitted parameter: :fishing") do
+      params.permit(book: [:pages])
+    end
+  end
+
+  test "logs on unexpected params" do
+    params = ActionController::Parameters.new(
+      book: { pages: 65 },
+      fishing: "Turnips",
+      car: "Mersedes")
+
+    assert_logged("Unpermitted parameters: :fishing, :car") do
+      params.permit(book: [:pages])
+    end
+  end
+
+  test "logs on unexpected nested param" do
+    params = ActionController::Parameters.new(
+      book: { pages: 65, title: "Green Cats and where to find then." })
+
+    assert_logged("Unpermitted parameter: :title") do
+      params.permit(book: [:pages])
+    end
+  end
+
+  test "logs on unexpected nested params" do
+    params = ActionController::Parameters.new(
+      book: { pages: 65, title: "Green Cats and where to find then.", author: "G. A. Dog" })
+
+    assert_logged("Unpermitted parameters: :title, :author") do
+      params.permit(book: [:pages])
+    end
+  end
+
+  private
+
+    def assert_logged(message)
+      old_logger = ActionController::Base.logger
+      log = StringIO.new
+      ActionController::Base.logger = Logger.new(log)
+
+      begin
+        yield
+
+        log.rewind
+        assert_match message, log.read
+      ensure
+        ActionController::Base.logger = old_logger
+      end
+    end
+end