Rails 6 error thrown in render - wrong number of arguments (given 2, expected 1)

[ishields]

Hello! I just updated to Rails 6 and have the latest version of the gem (2.12.0).

I'm experiencing an error in one of my rspec tests in which it looks the controller render method is passing the wrong number of arguments.

The test is very simple

describe HomeController do
  describe '#index' do
    it 'is successful and calls seo data' do
      expect(controller).to receive(:set_meta_tags)
      get :index
      expect(response).to be_successful
    end
  end
end

ActionView::Template::Error: wrong number of arguments (given 2, expected 1)

  0) HomeController #index is successful
     Failure/Error:[0mget[33m:index[0m

     ActionView::Template::Error:
       wrong number of arguments (given 2, expected 1)
     # /Users/myuser/.rvm/gems/ruby-2.6.3/gems/meta-tags-2.12.0/lib/meta_tags/controller_helper.rb:22:in `render'

I believe the offending method is in ControllerHelper in the render method

def render(*args, &block)
      meta_tags[:title]       = @page_title       if @page_title
      meta_tags[:keywords]    = @page_keywords    if @page_keywords
      meta_tags[:description] = @page_description if @page_description

      super 
end

I believe super is passing both args and block to the render method but the super render method is only expecting one argument. As a proof of concept I modified the call to be super(args) and that seemed to work. Not really sure if this is the solution though.

[kpumuk]

Hi! I checked the issue, and it seems like the problem is not in meta-tags, but in RSpec.

First of all, in Ruby you can pass a block to any method without consequences:

def a
  puts "Hello"
end

a { raise "Really?" }
# → Hello

Now, for your issue, if you turn on a backtrace in RSpec (--backtrace argument), last two lines will be:

     # /Users/kpumuk/.rvm/gems/ruby-2.6.3/gems/rspec-rails-3.8.2/lib/rspec/rails/view_rendering.rb:105:in `call'
     # /Users/kpumuk/.rvm/gems/ruby-2.6.3/gems/actionview-6.0.0/lib/action_view/template.rb:315:in `compile'

So, ActionView calls a handler with two arguments (link):

      def compile(mod)
        source = encode!
        code = @handler.call(self, source)

While RSpec overrides it with one argument (link):

      class EmptyTemplateHandler
        def self.call(_template)
          ::Rails.logger.info("  Template rendering was prevented by rspec-rails. Use `render_views` to verify rendered view contents if necessary.")

          %("")
        end
      end

This was already reported and fixed in RSpec 4.dev:

• EmptyTemplateHandler::call wrong number of arguments (2 for 1) rspec/rspec-rails#2161
• EmptyTemplateHandler fix arguments rspec/rspec-rails#2089

[ishields]

You're totally right. Switching to that branch worked. Really appreciate your quick reply on this.
Thanks a lot!

[kpumuk]

You're welcome :-)