Enable test coverage

Rakefile

@@ -7,4 +7,11 @@ Rake::TestTask.new do |t|
   t.libs.push 'test'
 end
 
+namespace :test do
+  task :coverage do
+    ENV['COVERAGE'] = 'true'
+    Rake::Task['test'].invoke
+  end
+end
+
 task default: :test

test/test_helper.rb

@@ -1,5 +1,21 @@
 require 'rubygems'
 require 'bundler/setup'
+
+if ENV['COVERAGE'] == 'true'
+  require 'simplecov'
+  require 'coveralls'
+
+  SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter[
+    SimpleCov::Formatter::HTMLFormatter,
+    Coveralls::SimpleCov::Formatter
+  ]
+
+  SimpleCov.start do
+    command_name 'test'
+    add_filter   'test'
+  end
+end
+
 require 'minitest/autorun'
 $:.unshift 'lib'
 require 'lotus/controller'