Add rubocop as a development and test dependency

rmacklin · rmacklin · commit ebf0f44e1c2c · 2019-03-30T11:51:48.000-07:00
diff --git a/Gemfile b/Gemfile
@@ -6,3 +6,7 @@ gemspec
 
 gem 'minitest', '~> 5.11'
 gem 'rake', '~> 12.3'
+
+group :development, :test do
+  gem 'rubocop'
+end
