diff --git a/Gemfile b/Gemfile
index 43cb8c3..c627e2c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,3 +2,4 @@ source "https://rubygems.org"
 gem "colored"
 gem "mocha"
 gem "parallel"
+gem "minitest"
diff --git a/Gemfile.lock b/Gemfile.lock
index f1afe56..6bca7df 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,15 +2,17 @@ GEM
   remote: https://rubygems.org/
   specs:
     colored (1.2)
-    metaclass (0.0.1)
-    mocha (0.10.0)
+    metaclass (0.0.2)
+    minitest (5.2.2)
+    mocha (1.0.0)
       metaclass (~> 0.0.1)
-    parallel (0.5.9)
+    parallel (0.9.2)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
   colored
+  minitest
   mocha
   parallel