> But wouldn't you want to update your project to a new(er) version of Ruby in that hypothetical? Perhaps because it's in maintenance mode and what you really

> But wouldn't you want to update your project to a new(er) version of Ruby in that hypothetical? Perhaps because it's in maintenance mode and what you really need is just to be able to run it to compare its behavior with that of its replacement, or because you want to perform the upgrade by replacing code that relies on deprecated APIs in an incremental way, in a copy of the codebase that still runs and passes tests at each step along the way. Or maybe you're a scientist and you want to run the original code because you want your tests to have the exact same performance and other characteristics as the code used in the original paper, so you want to avoid compiler/interpreter optimizations that have come out in the meantime.