Rust does not have manual memory management, and its type system also has the property that if your program compiles it probably works, IME.
So...yeah.
It was an MQTT server, and the tests basically went "if we have these subscriptions, then...", but no subscriptions ever got actually stored by the server.
multiply x y = x + y
then it will compile but not work, so they don't take it literally. But it is a pithy statement of the lived experience of many users of strongly typed programming, which is more accurately described by something like "if it compiles then it will probably do something at least basically sensible and often be pretty close to what you actually wanted".