# File actionpack/lib/action_dispatch/testing/test_process.rb, line 19
      def fixture_file_upload(path, mime_type = nil, binary = false)
        if self.class.respond_to?(:fixture_path) && self.class.fixture_path &&
            !File.exist?(path)
          original_path = path
          path = Pathname.new(self.class.fixture_path).join(path)

          if !self.class.file_fixture_path
            ActiveSupport::Deprecation.warn(<<~EOM)
              Passing a path to `fixture_file_upload` relative to `fixture_path` is deprecated.
              In Rails 6.2, the path needs to be relative to `file_fixture_path` which you
              haven't set yet. Set `file_fixture_path` to discard this warning.
            EOM
          elsif path.exist?
            non_deprecated_path = path.relative_path_from(Pathname(self.class.file_fixture_path))
            ActiveSupport::Deprecation.warn(<<~EOM)
              Passing a path to `fixture_file_upload` relative to `fixture_path` is deprecated.
              In Rails 6.2, the path needs to be relative to `file_fixture_path`.

              Please modify the call from
              `fixture_file_upload("#{original_path}")` to `fixture_file_upload("#{non_deprecated_path}")`.
            EOM
          else
            path = file_fixture(original_path)
          end
        elsif self.class.file_fixture_path && !File.exist?(path)
          path = file_fixture(path)
        end

        Rack::Test::UploadedFile.new(path, mime_type, binary)
      end