2 files changed, 60 insertions, 0 deletions
diff --git a/actionpack/test/controller/params_parse_test.rb b/actionpack/test/controller/params_parse_test.rb
new file mode 100644
index 0000000000..440ab06fd7
--- /dev/null
+++ b/actionpack/test/controller/params_parse_test.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+require "abstract_unit"
+
+class ParamsParseTest < ActionController::TestCase
+  class UsersController < ActionController::Base
+    def create
+      head :ok
+    end
+  end
+
+  tests UsersController
+
+  def test_parse_error_logged_once
+    log_output = capture_log_output do
+      post :create, body: "{", as: :json
+    end
+    assert_equal <<~LOG, log_output
+      Error occurred while parsing request parameters.
+      Contents:
+
+      {
+    LOG
+  end
+
+  private
+
+    def capture_log_output
+      output = StringIO.new
+      request.set_header "action_dispatch.logger", ActiveSupport::Logger.new(output)
+      yield
+      output.string
+    end
+end
diff --git a/actionpack/test/controller/rescue_test.rb b/actionpack/test/controller/rescue_test.rb
index 4ed79073e5..3c39373e55 100644
--- a/actionpack/test/controller/rescue_test.rb
+++ b/actionpack/test/controller/rescue_test.rb
@@ -70,6 +70,10 @@ class RescueController < ActionController::Base
     render plain: "io error"
   end
 
+  rescue_from ActionDispatch::Http::Parameters::ParseError do
+    render plain: "parse error", status: :bad_request
+  end
+
   before_action(only: :before_action_raises) { raise "umm nice" }
 
   def before_action_raises
@@ -130,6 +134,11 @@ class RescueController < ActionController::Base
     raise ResourceUnavailableToRescueAsString
   end
 
+  def arbitrary_action
+    params
+    render plain: "arbitrary action"
+  end
+
   def missing_template
   end
 
@@ -306,6 +315,23 @@ class RescueControllerTest < ActionController::TestCase
     get :exception_with_no_handler_for_wrapper
     assert_response :unprocessable_entity
   end
+
+  test "can rescue a ParseError" do
+    capture_log_output do
+      post :arbitrary_action, body: "{", as: :json
+    end
+    assert_response :bad_request
+    assert_equal "parse error", response.body
+  end
+
+  private
+
+    def capture_log_output
+      output = StringIO.new
+      request.set_header "action_dispatch.logger", ActiveSupport::Logger.new(output)
+      yield
+      output.string
+    end
 end
 
 class RescueTest < ActionDispatch::IntegrationTest