I belive this is an artefact of some earlier version of the library, where the generated code would be written directly to a file (or something along these lines). The actually used code path to start a file is [`compile`](https://github.com/protobuf-ruby/beefcake/blob/3c93d2f43f8c427ca4a7f51ada913487de3c212c/lib/beefcake/generator.rb#L274)