e4e1b62 broke `to_param` handling:

- There was an issue inside controller tests where order params were not respected, the reason
  was because we were calling `Hash#to_query` which sorts the results lexicographically.
  1e4e1b62 fixed that issue by not using `to_query` but instead a utility function provided by rack.
- However with the fix came another issue where it's now no longer possible to do this

  ```
   post :foo, params: { user: User.first }

   # Prior to the patch the controller will receive { "user" => "1" }
   # Whereas now you get { "user": "#<User: ...>" }
  ```

  The fix in this PR is to modify `Hash#to_query` to sort only when it
  doesn't contain an array structure that looks something like "bar[]"

  Ref https://github.com/rails/rails/pull/33341#issuecomment-404039396

1 files changed, 1 insertions, 1 deletions

diff --git a/actionpack/lib/action_controller/test_case.rb b/actionpack/lib/action_controller/test_case.rb
index 33b0bcbefe..5d784ceb31 100644
--- a/actionpack/lib/action_controller/test_case.rb
+++ b/actionpack/lib/action_controller/test_case.rb
@@ -109,7 +109,7 @@ module ActionController
           when :xml
             data = non_path_parameters.to_xml
           when :url_encoded_form
-            data = Rack::Utils.build_nested_query(non_path_parameters)
+            data = non_path_parameters.to_query
           else
             @custom_param_parsers[content_mime_type.symbol] = ->(_) { non_path_parameters }
             data = non_path_parameters.to_query