Enable minitest again

If you have skipped minitest/test-unit while creating a rails app with -T or want to move to minitest from rspec or want to start with minitest in an existing rails project without tests, its very easy.

Just include

    require "rails/test_unit/railtie"

in config/application.rb.

After this rake test will start working. You may have to create test folder structure on your own or can copy from an existing project with tests.