Make asset pipeline act like production on development

I am experiencing some problems with assets on production: missing ones, stuff compiled into the wrong files (javascript for "/admin" getting compiled into the frontend code and so on). Most of the assets come from engines. I want to debug and optimize this.

For that, I need to precompile, serve and fail on my development environment just like it is done on production.

I have added some lines to my config/development.rb:

  config.serve_static_assets = true
   config.assets.precompile += %w( store/all.js store/all.css admin/all.js admin/all.css ) # @TODO: clean up, and optimize.
   config.assets.compile = false
 

Running this with rake RAILS_GROUPS=assets RAILS_ENV=development assets:precompile gives me all the assets and the manifest.yml in public/.

But then the server fails:

Sprockets::Helpers::RailsHelper::AssetPaths::AssetNotPrecompiledError in Spree/home#index
 
 Showing /xxxx/app/views/spree/shared/_head.html.erb where line #13 raised:
 
 favicon.ico isn't precompiled
 

favicon.ico isn't precompiled. But it is! Its there, in the public dir, in manifest.yml, and I can fetch it with the browser (or wget): http://localhost:3000/assets/favicon.ico.

NOTE Favicon is simply the first asset called. If I strip out favicon, the problem simply surfaces with the next asset, being "all.js", or, when that is stripped, "all.css", and so on. I can strip it untill "footer_bg.png", and it will then fail there. Again: the problem is not favicon, but the fact that the development environment does not see the precompiled assets at all.

What more is needed to get development asset pipeline similar to production?

EDIT: More explicit explanation that favicon is not the problem, merely a symptom.

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