Possible regression in 4.0 regarding partials

[markokajzer]

I'm not sure if this was ever intended to work this way, but in 3.x you could use the component's methods and variables inside of a block passed to a partial. This does not seem to work in 4.0.

Example and reproduction repo below.
I'm sorry I could not grasp how to write up a PR with a failing test :(((

Is there a way to re-enable this behaviour? And if not, how would you handle it?

Steps to reproduce

Reproduction repo

bin/rails test test/components/test_component_test.rb

Inline example:

# app/components/test_component.rb
class TestComponent < ViewComponent::Base
  def initialize(title:)
    @title = title
  end

  attr_reader :title
end

# app/components/test_component.html.erb
<%= render "shared/card" do %>
  <%= title %>
<% end %>

# app/views/shared/_card.html.erb
<div>
  <%= yield %>
</div>

# app/components/test_component_test.rb
def test_component_renders_something_useful
  assert_includes(
    render_inline(TestComponent.new(title: "Hello, world!")).to_html,
    "Hello, world!"
  )
end

Test passes in 3.x (see previous commit in reproduction repo), but fails in 4.0

Expected behavior

title inside of block passed to card partial resolves to title passed to TestComponent

Actual behavior

Partial context does not have access to TestComponent context.
@title is nil
title method is not defined

Backtrace:

ActionView::Template::Error: undefined method `title' for an instance of #<Class:0x0000000125f70280>
    app/components/test_component.html.erb:2:in `block in call'
    app/views/shared/_card.html.erb:2
    app/components/test_component.html.erb:1:in `call'
    test/components/test_component_test.rb:8:in `test_component_renders_something_useful'

System configuration

Rails version: 8.0.2.1

Ruby version: 3.3.6

Gem version: 4.0.2 (works in 3.x)

[markokajzer]

Looks like this might be somewhat related to #2413