diff --git a/.gitignore b/.gitignore
index 85d89b4a1fd303ab00c5ac3ab809c808cc4b3f5a..a7b9db09bb81cb92f9aa9fbd76bc889f74a025c7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,3 +16,4 @@ server.rb
 *.sw?
 /tmp/
 /_yardoc/
+.idea/
diff --git a/Gemfile b/Gemfile
index b4e2a20bb6069d33479542fc863e7e36810e0f01..9c886f687c742260ee1a06b1f7a704a6d4fe2d2e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,7 @@
 source "https://rubygems.org"
 
 gemspec
+
+group :development do
+  gem 'minitest', '~> 5.8', '>= 5.8.4'
+end