Avoid passing {format:nil} from form_for/form_with to polymorphic_path

[cryptoque]

Summary

In #43421 part of the functionalities of form_for was delegated to form_with, this could potentially cause some issues in that the following code in form_for:

if options[:url] != false
  options[:url] ||= if options.key?(:format)
    polymorphic_path(record, format: options.delete(:format))
  else
    polymorphic_path(record, {})
  end
end

is removed and replace with functionality inside form_with:

if url != false
  url ||= polymorphic_path(model, format: format)
end

This caused some noticeable issues in the latest rails upgrade for GitHub. As when format is not passed, polymorphic_path(model, {format: nil}) is called instead of the original polymorphic_path(model, {}) and

if options.empty?
  recipient.public_send(method, *args)
else
  recipient.public_send(method, *args, options)
end

and the extra options in recipient.public_send(method, *args, options) is potentially a breaking change for the underlying method.

This PR adds back the condition to pass {} if option is empty in form_with and added a test to make sure it doesn't break form_with.

Other Information

Thanks to @TooManyBees for help with debug this 🙇‍♀️

[jhawthorn]

Should this behave differently if called as form_with(format: nil) instead of form_with() (without a format?). It looks like the old code in was using options.key? and options.delete

IMO it seems fine that format: nil is the same as unspecified, but if that has a difference to polymorphic_path maybe it is significant.

[cryptoque]

IMO it seems fine that format: nil is the same as unspecified, but if that has a difference to polymorphic_path maybe it is significant.

Personally I think it should be fine given that the only real usage of the format:nil within polymorphic_path (via method polymorphic_method) is it being passed on as part of options to the method:

if options.empty?
   recipient.public_send(method, *args)
else
    recipient.public_send(method, *args, options)
end

I think most likely the method itself can handle the difference between format:nil vs format not specified, as format:nil isn't a meaningful thing to pass on... and there is likely a default value if a method is expecting a format.

[kaspth]

I was curious to see if we could implement this as polymorphic_path(model, { format: format }.compact).

But then I noticed that I can't get the test to fail if I change the code back to the version before this PR. @cryptoque can you double-check the test to see if it needs tweaking?

3.0.2 ~/code/rails/actionview main *= bin/test test/template/form_helper_test.rb -n /new_form_for_without_format/
Running 305 tests in parallel using 8 processes
Run options: -n /new_form_for_without_format/ --seed 41714

# Running:

.

Finished in 0.204844s, 4.8818 runs/s, 4.8818 assertions/s.
1 runs, 1 assertions, 0 failures, 0 errors, 0 skips

[cryptoque]

@kaspth that is good point, I will modify the test on Monday.