Rspec-rails: Using fixture_file_upload with rspec-rails

What Ruby, Rails and RSpec versions are you using?

Ruby version: 2.7.2
Rails version: 6.1.0
RSpec version: 3.10.1 (rspec-core) and 4.0.2 (rspec-rails)

Observed behaviour

Hello! I am trying to upgrade my app to Rails 6.1 from 6.0.3.4, and I'm encountering an error when using the fixture_file_upload method. When I call this method, the following exception is raised:

     NoMethodError:
       undefined method `file_fixture_path' for RSpec::Rails::FixtureFileUploadSupport::RailsFixtureFileWrapper:Class
       Did you mean?  fixture_path

It seems that ActionPack has changed the implementation of the fixture_file_upload and expects there to be a file_fixture_path method on the RailsFixtureFileWrapper class.

Expected behaviour

I expect this method to upload the file without raising any exceptions.

Can you provide an example app?

You can see my example app with a failing test here: https://github.com/egiurleo/fixture-file-upload-test/blob/main/spec/fixture_file_upload_spec.rb

For the test, I have a pdf file in the spec/fixtures folder. I am trying to call the fixture_file_upload method with the name of that file, and the test raises the exception I described earlier.

Notes

• I may just be using this method wrong, but I can't find any documentation that explains how to set file_fixture_path in this context so any guidance would be appreciated.
• The actual change was in ActionPack (lib/action_dispatch/testing/test_process.rb).
• Thank you for your time!