Where the Rails' asset pipeline searches for asset files and how the config.assets.precompile directive works

rails_asset_pipeline_compiled_files.rb

# Test the result of config.assets.precompile
#
# Check which files will be regarded as "manifests" and thus precompiled and be
# available for standalone use via the /assets/<asset> URL when in production.
# Execute this code in your Rails console.

# First, you'll probably be in development mode, so add here your
# additional production precompile patterns you want to test against.
precompile = Rails.configuration.assets.precompile + [/^.+\.css$/, 'active_admin.js']

# Temporary hack so that we can test easily for procs too.
# Please don't let this get out of your development console :-)
class Proc; def ===(other); call(other); end; end

# Now run the check; the list you see printed is the list of *all*
# assets you can include individually while in production mode, e.g. via
# image_tag('name'), javascript_include_tag('name'), stylesheet_include_tag('name') etc.
Rails.application.assets.each_logical_path { |asset_path| puts asset_path if precompile.any? { |rule| rule === asset_path } }; nil

rails_asset_pipeline_paths.rb

# Find out the list of assets available for packaging for your app.
#
# This one is important, because these path segments are used by the assets:precompile
# Rake task when preparing your manifest assets. The rules to match them can be found in
# production.rb, in the config.assets.precompile setting.
#
# Find out more details about this here:
#   https://github.com/rails/rails/blob/v3.1.3/actionpack/lib/sprockets/static_compiler.rb#L18
Rails.application.assets.each_logical_path { |asset_path| puts asset_path }; nil

# Or which paths are searched for assets:
Rails.application.assets.paths.each { |path| puts path }; nil