Use SimpleCov in addition to publishing to Coveralls.io

spec/spec_helper.rb

@@ -1,8 +1,15 @@
 require 'rubygems'
 require 'rspec'
 require 'singleton'
+require 'simplecov'
 require 'coveralls'
-Coveralls.wear!
+
+# Both local SimpleCov and publish to Coveralls.io
+SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter[
+  SimpleCov::Formatter::HTMLFormatter,
+  Coveralls::SimpleCov::Formatter
+]
+SimpleCov.start
 
 test_dir = File.dirname(__FILE__)
 $LOAD_PATH.unshift test_dir unless $LOAD_PATH.include?(test_dir)