tests: add SimpleCov for test coverage

.simplecov

@@ -0,0 +1,2 @@
+SimpleCov.start do
+end

Gemfile

@@ -33,6 +33,7 @@ group :test do
   gem 'rubocop'
   gem 'rdoc'
   gem 'bundler-audit'
+  gem 'simplecov', require: false
 end
 
 # Needed for debugging WhatWeb

Rakefile

@@ -21,7 +21,8 @@ task :default => :unit
 
 Rake::TestTask.new(:unit) do |t|
   t.description = 'Run unit tests'
-  t.test_files = FileList['test/unit/test_*.rb']
+  t.test_files = FileList['test/enable_coverage.rb', 'test/unit/test_*.rb']
+  t.verbose = true
 end
 
 Rake::TestTask.new(:integration) do |t|

test/enable_coverage.rb

@@ -0,0 +1 @@
+require 'simplecov'