Ruby 单独运行某个unittest

refer to:
https://stackoverflow.com/questions/1506780/how-to-run-a-single-test-from-a-rails-test-suite

bundle exec ruby -I test test/models/cell_input_test.rb

单独运行某个test case:

ruby -I test test/unit/my_model_test.rb -n test_name

对于

test 'xx yy' do  ... end  这样的，则是：

ruby -I test test/unit/my_model_test.rb -n test_xx_yy