form_with default argument raises exception on Rails 8.0

[grantbdev]

Steps to reproduce*

Use form_with in a view without specifying a model and without specifying validate: true:

<%= form_with(url: "/posts") do |form| %>
  <%# form stuff goes here %>
<% end %>

Here is a regression test for test/action_view/cases/test_form_with_helpers.rb:

def test_form_with_without_model_without_validation
  form_with(url: '/posts') do |f|
    concat f.text_field(:cost)
  end

  expected = whole_form_with('/posts') do
    form_field('input', id: 'cost', name: 'cost', type: 'text')
  end

  assert_dom_equal expected, output_buffer
end

Expected behavior*

The Rails fallback behavior should be used without any problem, like when the gem is not installed.

Actual behavior*

Deprecation warning on Rails 7.2:

DEPRECATION WARNING: Passing nil to the :model argument is deprecated and will raise in Rails 8.0

Exception raised on Rails 8.0+:

ArgumentError: Passed nil to the :model argument, expect an object or false

System configuration*

Rails version: 7.2+

Ruby version: 3.3

Client Side Validations version: 22.3.0

---

I think this problem can be solved by changing the default model option in form_with to false to match the expected Rails default:
https://github.com/DavyJonesLocker/client_side_validations/blob/v22.3.0/lib/client_side_validations/action_view/form_with_helper.rb#L7

I don't suspect there would be a backwards compatibility issue with this change.

The Rails change was initially made here: rails/rails#49943
It was changed to a deprecation warning for Rails 7.2 here: rails/rails#50931

[tagliala]

Hi @grantbdev,

thanks for this issue

It is unfortunate that none of the existing tests is catching this or the deprecation, not even with RUBYOPT="-w"

If you want to contribute with a PR, feel free to add the test and submit it and I will take a look. Otherwise I can take a look in the upcoming days

[grantbdev]

Thank you for the work on this @maxnovee and @tagliala!