Unit tests are trivial because you can probably use a single arena that is only reset once at the end of the test. Unless the test is specifically to stress tes

Unit tests are trivial because you can probably use a single arena that is only reset once at the end of the test. Unless the test is specifically to stress test memory in some form. > I assume the receiver then has to know it has to clone all of those values, yes? The receiver needs to understand the lifetime any which way. If you parse a large JSON blob and wish to retain arbitrary key/values you have to understand how long they're valid for. If you're using a garbage collection language you can not worry about it (you just have to worry about other things!). You can think about it less if the key/values are ref-counted. But for most C-like language implementations you probably have to retain either the entire parsed structure or clone the key/values you care about.