Import ActionController::MissingRenderer from Rails

[zzak]

Happened upon this exception when patching this file in rails/rails#48327, the documentation references a method which was moved to this gem, and nothing else in Rails uses it internally.

I think we can move it here and deprecate it from Rails, which I've started working on in rails/rails#48328

[carlosantoniodasilva]

@zzak I can get this into responders and released, but we'll have to update the Rails side of things a bit apparently... we might also have to detect here if the constant is not already defined or something (suppressing possible warnings), I think?

[zzak]

@carlosantoniodasilva Thanks for the ping, yeah I'm not sure but maybe we can do unless defined??

I have to fix the tests (and probably rebase) upstream too, but I think the right thing to do is do the check on responders side.

[zzak]

@carlosantoniodasilva Finally got around to this again, and after fixing the deprecation on Rails side, I think the best path forward is to rename the constant inside this gem.

If someone is using an unpatched version of the responders gem, AND updated to a version of Rails with the deprecation, they will see this warning:

DEPRECATION WARNING: ActionController::MissingRenderer is deprecated and will be removed in Rails 8.2. (called from test_raises_missing_renderer_if_an_api_behavior_with_no_renderer at /home/zzak/code/responders/test/action_controller/respond_with_test.rb:726)
F

Failure:
RespondWithControllerTest#test_raises_missing_renderer_if_an_api_behavior_with_no_renderer [test/action_controller/respond_with_test.rb:726]:
[ActionController::DeprecatedMissingRenderer] exception expected, not
Class: <NameError>
Message: <"uninitialized constant ActionController::Responder::MissingRenderer">
---Backtrace---
/home/zzak/code/responders/lib/action_controller/responder.rb:225:in `api_behavior'
/home/zzak/code/responders/lib/action_controller/responder.rb:207:in `rescue in to_format'
/home/zzak/code/responders/lib/action_controller/responder.rb:198:in `to_format'
/home/zzak/code/responders/lib/action_controller/responder.rb:177:in `respond'
/home/zzak/code/responders/lib/action_controller/responder.rb:170:in `call'
/home/zzak/code/responders/lib/action_controller/respond_with.rb:216:in `respond_with'
/home/zzak/code/responders/test/action_controller/respond_with_test.rb:128:in `index'
/home/zzak/code/rails/actionpack/lib/action_controller/metal/basic_implicit_render.rb:8:in `send_action'
/home/zzak/code/rails/actionpack/lib/abstract_controller/base.rb:234:in `process_action'
/home/zzak/code/rails/actionpack/lib/action_controller/metal/rendering.rb:199:in `process_action'
/home/zzak/code/rails/actionpack/lib/abstract_controller/callbacks.rb:261:in `block in process_action'
/home/zzak/code/rails/activesupport/lib/active_support/callbacks.rb:100:in `run_callbacks'
/home/zzak/code/rails/actionpack/lib/abstract_controller/callbacks.rb:260:in `process_action'
/home/zzak/code/rails/actionpack/lib/action_controller/metal/rescue.rb:27:in `process_action'
/home/zzak/code/rails/actionpack/lib/action_controller/metal/instrumentation.rb:76:in `block in process_action'
/home/zzak/code/rails/activesupport/lib/active_support/notifications.rb:212:in `instrument'
/home/zzak/code/rails/actionpack/lib/action_controller/metal/instrumentation.rb:75:in `process_action'
/home/zzak/code/rails/actionpack/lib/action_controller/metal/params_wrapper.rb:259:in `process_action'
/home/zzak/code/rails/actionpack/lib/abstract_controller/base.rb:167:in `process'
/home/zzak/code/rails/actionview/lib/action_view/rendering.rb:40:in `process'
/home/zzak/code/rails/actionpack/lib/action_controller/metal.rb:252:in `dispatch'
/home/zzak/code/rails/actionpack/lib/action_controller/test_case.rb:639:in `block in process_controller_response'
/home/zzak/code/rails/actionpack/lib/action_controller/test_case.rb:631:in `wrap_execution'
/home/zzak/code/rails/actionpack/lib/action_controller/test_case.rb:639:in `process_controller_response'
/home/zzak/code/rails/actionpack/lib/action_controller/test_case.rb:549:in `process'
/home/zzak/.rbenv/versions/3.3.6/lib/ruby/gems/3.3.0/gems/rails-controller-testing-1.0.5/lib/rails/controller/testing/template_assertions.rb:62:in `process'
/home/zzak/code/rails/actionpack/lib/action_controller/test_case.rb:440:in `get'
/home/zzak/code/responders/test/action_controller/respond_with_test.rb:727:in `block in test_raises_missing_renderer_if_an_api_behavior_with_no_renderer'
---------------


bin/rails test /home/zzak/code/responders/test/action_controller/respond_with_test.rb:724

That was before I renamed it internally, I don't think is a problem, if someone is catching this error manually they will also get the warning.

The solution will be to update the responders gem with this patch and replace the constant if being called directly.

There is a gap however, if someone skips the version of Rails which emits the deprecation warning AND has an unpatched responders gem their code may break -- but that is an acceptable trade-off and people should perform upgrades gradually without skipping.

[carlosantoniodasilva]

@zzak I guess one potential issue is that if they're catching this error in their own code, it might break if we raise a different one on a new responders gem (if they just upgrade responders)

We could maybe inherit from ActionController::MissingRenderer for all existing Rails versions, and just define our own as you have today otherwise?