Merge pull request #96 from schneems/schneems/raise-on-dependencies

[Fix #95] Raise When Dependencies Improperly Used

Author: Rafael Mendonça França

lib/sprockets/rails/helper.rb

@@ -5,6 +5,14 @@
 module Sprockets
   module Rails
     module Helper
+      class DependencyError <StandardError
+        def initialize(path, dep)
+          msg = "Asset depends on '#{dep}' to generate properly but has not declared the dependency\n"
+          msg << "Please add: `//= depend_on_asset \"#{dep}\"` to '#{path}'"
+          super msg
+        end
+      end
+
       if defined? ActionView::Helpers::AssetUrlHelper
         include ActionView::Helpers::AssetUrlHelper
         include ActionView::Helpers::AssetTagHelper
@@ -36,7 +44,14 @@ def self.extended(obj)
         end
       end
 
+      def check_dependencies!(dep)
+        return unless @_dependency_assets
+        return if     @_dependency_assets.detect { |asset| asset.include?(dep) }
+        raise DependencyError.new(self.pathname, dep)
+      end
+
       def compute_asset_path(path, options = {})
+        check_dependencies!(path)
         if digest_path = asset_digest_path(path)
           path = digest_path if digest_assets
           path += "?body=1" if options[:debug]

test/fixtures/error/dependency.js.erb

@@ -0,0 +1 @@
+<%= asset_path("bar.js") %>

test/fixtures/logo.png

@@ -1 +1,2 @@
+//= depend_on_asset "logo.png"
 p { background: url(<%= image_path "logo.png" %>); }

test/fixtures/url.css.erb

@@ -1 +1,2 @@
+//= depend_on_asset "foo.js"
 var url = '<%= javascript_path :foo %>';

test/fixtures/url.js.erb

@@ -21,7 +21,7 @@ def setup
     @view = ActionView::Base.new
     @view.extend ::Sprockets::Rails::Helper
     @view.assets_environment = @assets
-    @view.assets_prefix = "/assets"
+    @view.assets_prefix      = "/assets"
 
     # Rails 2.x
     unless @view.respond_to?(:config)
@@ -30,10 +30,11 @@ def setup
     end
 
     @assets.context_class.assets_prefix = @view.assets_prefix
-    @assets.context_class.config = @view.config
+    @assets.context_class.config        = @view.config
 
     @foo_js_digest  = @assets['foo.js'].digest
     @foo_css_digest = @assets['foo.css'].digest
+    @logo_digest    = @assets["logo.png"].digest
   end
 
   def test_truth
@@ -169,7 +170,7 @@ def test_stylesheet_path
 
   def test_asset_url
     assert_equal "var url = '//assets.example.com/assets/foo.js';\n", @assets["url.js"].to_s
-    assert_equal "p { background: url(//assets.example.com/images/logo.png); }\n", @assets["url.css"].to_s
+    assert_equal "p { background: url(//assets.example.com/assets/logo.png); }\n", @assets["url.css"].to_s
   end
 end
 
@@ -222,7 +223,7 @@ def test_asset_digest
 
   def test_asset_url
     assert_equal "var url = '/assets/foo.js';\n", @assets["url.js"].to_s
-    assert_equal "p { background: url(/images/logo.png); }\n", @assets["url.css"].to_s
+    assert_equal "p { background: url(/assets/logo.png); }\n", @assets["url.css"].to_s
   end
 end
 
@@ -279,7 +280,7 @@ def test_asset_digest_path
 
   def test_asset_url
     assert_equal "var url = '/assets/foo-#{@foo_js_digest}.js';\n", @assets["url.js"].to_s
-    assert_equal "p { background: url(/images/logo.png); }\n", @assets["url.css"].to_s
+    assert_equal "p { background: url(/assets/logo-#{@logo_digest}.png); }\n", @assets["url.css"].to_s
   end
 end
 
@@ -381,3 +382,11 @@ def test_asset_digest
     assert_equal @foo_css_digest, @view.asset_digest("foo.css")
   end
 end
+
+class ErrorsInHelpersTest < HelperTest
+  def test_dependency_error
+    assert_raise Sprockets::Rails::Helper::DependencyError do
+      @assets['error/dependency.js'].to_s
+    end
+  end
+end