This illustrates one of the biggest downsides of dynamic languages - refactoring. Compile-time checking saves you from having to detect copy/paste/delete errors at runtime. A good IDE can help, but it's no substitute.
This is especially problematic in Ruby, as the author mentions, as the language is so dynamic that you're stuck having to write 100% coverage to ensure that variables are even named correctly.
This is especially problematic in Ruby, as the author mentions, as the language is so dynamic that you're stuck having to write 100% coverage to ensure that variables are even named correctly.