Fix current_page? when URL has trailing slash

This fixes the `current_page?` helper when the given URL has a trailing
slash, and is an absolute URL or also has query params.

Fixes #33956.

Co-authored-by: Rien Maertens <rien.maertens@posteo.be>

actionview/lib/action_view/helpers/url_helper.rb

@@ -573,16 +573,14 @@ module ActionView
         request_uri = url_string.index("?") || check_parameters ? request.fullpath : request.path
         request_uri = URI::DEFAULT_PARSER.unescape(request_uri).force_encoding(Encoding::BINARY)
 
-        if url_string.start_with?("/") && url_string != "/"
-          url_string.chomp!("/")
-          request_uri.chomp!("/")
+        if %r{^\w+://}.match?(url_string)
+          request_uri = +"#{request.protocol}#{request.host_with_port}#{request_uri}"
         end
 
-        if %r{^\w+://}.match?(url_string)
-          url_string == "#{request.protocol}#{request.host_with_port}#{request_uri}"
-        else
-          url_string == request_uri
-        end
+        remove_trailing_slash!(url_string)
+        remove_trailing_slash!(request_uri)
+
+        url_string == request_uri
       end
 
       if RUBY_VERSION.start_with?("2.7")
@@ -802,6 +800,11 @@ module ActionView
 
           params.sort_by { |pair| pair[:name] }
         end
+
+        def remove_trailing_slash!(url_string)
+          trailing_index = (url_string.index("?") || 0) - 1
+          url_string[trailing_index] = "" if url_string[trailing_index] == "/"
+        end
     end
   end
 end

actionview/test/template/url_helper_test.rb

@@ -625,6 +625,14 @@ class UrlHelperTest < ActiveSupport::TestCase
     @request = request_for_url("/posts")
 
     assert current_page?("/posts/")
+    assert current_page?("http://www.example.com/posts/")
+  end
+
+  def test_current_page_with_trailing_slash_and_params
+    @request = request_for_url("/posts?order=desc")
+
+    assert current_page?("/posts/?order=desc")
+    assert current_page?("http://www.example.com/posts/?order=desc")
   end
 
   def test_current_page_with_not_get_verb