public_* API is not desired

- Use `public_folder: true` instead.
- Allow configurable deprecation/error behavior via **`config.assets.unknown_asset_fallback`**

When set to a truthy value, the a result will be returned even if the requested asset is not found in the asset pipeline. When set to `false` it will raise an error.

Author: schneems

README.md

@@ -48,9 +48,12 @@ Each asset task will invoke `assets:environment` first. By default this loads th
 
 Also see [Sprockets::Rails::Task](https://github.com/rails/sprockets-rails/blob/master/lib/sprockets/rails/task.rb) and [Rake::SprocketsTask](https://github.com/rails/sprockets/blob/master/lib/rake/sprocketstask.rb).
 
-
 ### Initializer options
 
+**`config.assets.unknown_asset_fallback`**
+
+When set to a truthy value, the a result will be returned even if the requested asset is not found in the asset pipeline. When set to `false` it will raise an error.
+
 **`config.assets.precompile`**
 
 Add additional assets to compile on deploy. Defaults to `application.js`, `application.css` and any other non-js/css file under `app/assets`.

lib/sprockets/rails/helper.rb

@@ -6,6 +6,7 @@
 module Sprockets
   module Rails
     module Helper
+      class AssetNotFound < StandardError; end
       class AssetNotPrecompiled < StandardError
         include Sprockets::Rails::Utils
         def initialize(source)
@@ -33,7 +34,8 @@ def initialize(source)
         :assets_environment, :assets_manifest,
         :assets_precompile, :precompiled_asset_checker,
         :assets_prefix, :digest_assets, :debug_assets,
-        :resolve_assets_with, :check_precompiled_asset
+        :resolve_assets_with, :check_precompiled_asset,
+        :unknown_asset_fallback
       ]
 
       def self.included(klass)
@@ -76,27 +78,19 @@ def compute_asset_path(path, options = {})
         if asset_path = resolve_asset_path(path, debug)
           File.join(assets_prefix || "/", legacy_debug_path(asset_path, debug))
         else
-          result = super
+          message =  "The asset #{ path.inspect } you are looking for is not present in the asset pipeline."
+          raise AssetNotFound, message unless unknown_asset_fallback
+
           if respond_to?(:public_compute_asset_path)
-            throw(:asset_not_found, result)
-          else
-            result
-          end
-        end
-      end
+            message << "The public fallback behavior is being deprecaed and will be removed.\n"
+            message << "pass in `public_folder: true` instead.\n"
 
-      # Writes over the built in ActionView::Helpers::AssetUrlHelper#asset_path
-      # to use the asset pipeline.
-      def asset_path(*args)
-        catch_asset_not_found = catch(:asset_not_found) do
-          return super(*args)
+            call_stack = respond_to?(:caller_locations) ? caller_locations : caller
+            ActiveSupport::Deprecation.warn(message, call_stack)
+          end
+          super
         end
-
-        result = catch_asset_not_found
-        deprecate_invalid_asset_lookup(result, respond_to?(:caller_locations) ? caller_locations : caller)
-        result
       end
-      alias_method :path_to_asset, :asset_path # aliased to avoid conflicts with an asset_path named route
 
       # Resolve the asset path against the Sprockets manifest or environment.
       # Returns nil if it's an asset we don't know about.

lib/sprockets/railtie.rb

@@ -122,6 +122,7 @@ def configure(&block)
     config.assets.cache_limit = 50.megabytes
     config.assets.gzip        = true
     config.assets.check_precompiled_asset = true
+    config.assets.unknown_asset_fallback  = true
 
     config.assets.configure do |env|
       config.assets.paths.each { |path| env.append_path(path) }
@@ -245,7 +246,7 @@ def self.build_manifest(app)
         self.resolve_assets_with = config.assets.resolve_with
 
         self.check_precompiled_asset = config.assets.check_precompiled_asset
-
+        self.unknown_asset_fallback  = config.assets.unknown_asset_fallback
         # Expose the app precompiled asset check to the view
         self.precompiled_asset_checker = -> logical_path { app.asset_precompiled? logical_path }
       end

test/test_helper.rb

@@ -28,6 +28,7 @@ def setup
     @view.assets_precompile   = %w( manifest.js )
     precompiled_assets = @manifest.find(@view.assets_precompile).map(&:logical_path)
     @view.check_precompiled_asset = true
+    @view.unknown_asset_fallback  = true
     @view.precompiled_asset_checker = -> logical_path { precompiled_assets.include? logical_path }
     @view.request = ActionDispatch::Request.new({
       "rack.url_scheme" => "https"