From 3ec8ddd0cf3851fd0abfc45fd430b0de19981547 Mon Sep 17 00:00:00 2001
From: John Hawthorn <john@hawthorn.email>
Date: Mon, 17 Aug 2020 10:22:57 -0700
Subject: [PATCH] Avoid module_eval on helpers from AV::TestCase

Previously we were using module_eval to manually add some helpers in
ActionView::TestCase, which assumes a lot about what _helpers allows.

Instead, we can use a standard helper block to define these methods only
one time, and add a method to the new uniq controller class to tie back
to the test instance.
---
 actionview/lib/action_view/test_case.rb | 36 ++++++++++---------------
 1 file changed, 14 insertions(+), 22 deletions(-)

diff --git a/actionview/lib/action_view/test_case.rb b/actionview/lib/action_view/test_case.rb
index 3aa6af0893..c93cf64d6e 100644
--- a/actionview/lib/action_view/test_case.rb
+++ b/actionview/lib/action_view/test_case.rb
@@ -102,7 +102,8 @@ module ActionView
       end
 
       def setup_with_controller
-        @controller = Class.new(ActionView::TestCase::TestController).new
+        controller_class = Class.new(ActionView::TestCase::TestController)
+        @controller = controller_class.new
         @request = @controller.request
         @view_flow = ActionView::OutputFlow.new
         # empty string ensures buffer has UTF-8 encoding as
@@ -110,8 +111,8 @@ module ActionView
         @output_buffer = ActiveSupport::SafeBuffer.new ""
         @rendered = +""
 
-        make_test_case_available_to_view!
-        say_no_to_protect_against_forgery!
+        test_case_instance = self
+        controller_class.define_method(:_test_case) { test_case_instance }
       end
 
       def config
@@ -161,6 +162,16 @@ module ActionView
       included do
         setup :setup_with_controller
         ActiveSupport.run_load_hooks(:action_view_test_case, self)
+
+        helper do
+          def protect_against_forgery?
+            false
+          end
+
+          def _test_case
+            controller._test_case
+          end
+        end
       end
 
     private
@@ -169,25 +180,6 @@ module ActionView
         Nokogiri::HTML::Document.parse(@rendered.blank? ? @output_buffer : @rendered).root
       end
 
-      def say_no_to_protect_against_forgery!
-        _helpers.module_eval do
-          silence_redefinition_of_method :protect_against_forgery?
-          def protect_against_forgery?
-            false
-          end
-        end
-      end
-
-      def make_test_case_available_to_view!
-        test_case_instance = self
-        _helpers.module_eval do
-          unless private_method_defined?(:_test_case)
-            define_method(:_test_case) { test_case_instance }
-            private :_test_case
-          end
-        end
-      end
-
       module Locals
         attr_accessor :rendered_views