Properly register with app.assets if available or Sprockets otherwise

jade.gemspec

@@ -24,4 +24,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rspec'
   s.add_development_dependency 'rails', '>= 3.1'
   s.add_development_dependency 'pry'
+  s.add_development_dependency 'sqlite3'
 end

lib/jade/engine.rb

@@ -4,8 +4,8 @@
 module Jade
   class Engine < Rails::Engine
     initializer "jade.configure_rails_initialization", :before => 'sprockets.environment', :group => :all do |app|
-      next unless app.config.assets.enabled
-      Sprockets.register_engine '.jade', ::Jade::Template
+      sprockets = app.assets || Sprockets
+      sprockets.register_engine '.jade', ::Jade::Template
     end
   end
 end

spec/source_spec.rb

@@ -2,11 +2,11 @@
 
 describe Jade::Source do
   it "should contain jade asset" do
-    File.exist?(Jade::Source::jade_path).should be_true
+    File.exist?(Jade::Source::jade_path).should be_truthy
   end
 
   it "should contain runtime asset" do
-    File.exist?(Jade::Source::runtime_path).should be_true
+    File.exist?(Jade::Source::runtime_path).should be_truthy
   end
 
   it "should be able to read jade source" do
@@ -16,4 +16,4 @@
   it "should be able to read runtime source" do
     IO.read(Jade::Source::runtime_path).should_not be_empty
   end
-end
+end

spec/template_spec.rb

@@ -15,7 +15,7 @@ def template(source, file)
 
   it 'should be served' do
     assets.should serve 'sample.js'
-    asset_for('sample.js').body.should include "Yap, it works"
+    asset_for('sample.js').to_s.should include "Yap, it works"
   end
 
   it 'should work fine with JST' do