Adding Jammit::Packager#includes? to detect existence of compiled assets.

lib/jammit/packager.rb

@@ -70,6 +70,13 @@ def individual_urls(package, extension)
       package_for(package, extension)[:urls]
     end
 
+    # Determines the existence of a packaged asset in the assets.yml file.
+    def includes?(package, extension)
+      !!package_for(package.to_sym, extension.to_sym)
+    rescue PackageNotFound
+      false
+    end
+
     def compressor
       @compressor ||= Compressor.new
     end

test/unit/test_packager.rb

@@ -33,6 +33,19 @@ def test_fetching_lists_of_nested_urls
     assert urls == ['/assets/jst_test_nested.jst']
   end
 
+  def test_package_includes
+    assert Jammit.packager.includes?(:css_test, :css)
+    assert Jammit.packager.includes?("css_test_nested", "css")
+    assert Jammit.packager.includes?(:js_test, :js)
+    assert Jammit.packager.includes?("js_test_nested", "js")
+    assert Jammit.packager.includes?(:jst_test, :js)
+    assert Jammit.packager.includes?("jst_test_nested", "js")
+
+    assert !Jammit.packager.includes?(:not_included_file, :js)
+    assert !Jammit.packager.includes?(:test1, :css)
+    assert !Jammit.packager.includes?(:"nested/nested1", :js)
+  end
+
   def test_packaging_stylesheets
     css = Jammit.packager.pack_stylesheets(:css_test)
     assert css == File.read('test/fixtures/jammed/css_test.css')
@@ -129,5 +142,4 @@ def test_packaging_javascripts_with_package_names
     assert File.read('test/public/assets/js_test.js') == File.read('test/fixtures/jammed/js_test_package_names.js')
     FileUtils.rm_rf("test/public/assets")
   end
-
 end