Fix coverage reporter

Author: andrew

Rakefile

@@ -3,6 +3,8 @@
 require "bundler/gem_tasks"
 require "minitest/test_task"
 
-Minitest::TestTask.create
+Minitest::TestTask.create do |t|
+  t.test_prelude = 'require "test_helper"'
+end
 
 task default: :test