[TUHS] UNIX testing / error injection

[Adam Koszek via TUHS]

Hello,

A friend told me that UNIX engineers went through great pains to test software. I heard a story about bubble gum wrapper being stuck into IDE disk cable to short some lines to inject errors, and see if the filesystem would handle/survive this.

Were there any more examples of this?

After UNIX was already running many program, were any of the complex pieces of system code ever developed in the user-space first? Filesystems/schedulers/networking are inherently hard to get right, and the compile -> boot -> see kernel fail wasn’t ever fun cycle for me, and it had to be hell on slow machines..

How was all this good code delivered? :)

I’ve learnt a buzzword: “deterministic simulation testing”. It’s when you stub everything and run program in a fully controllable virtual world, and can inject faults etc. These days I can build mini datacenter in a single Golang program, but I’m wondering how the software that came before was developed.

Adam