NoMethodError：运行辅助测试时未定义的方法`scan'

I have a helper that truncates a user's full-name to only show their first name. I wrote a little test to just be sure that it works. I'm forcing myself to learn to test rigorously early on, so this may be overkill but I'm trying to learn a bit more about testing various aspects of the application. I have a helper that truncates a user's full-na