[TUHS] UNIX testing / error injection

[segaloco via TUHS]

On Wednesday, April 15th, 2026 at 09:47, Dan Cross via TUHS <tuhs at tuhs.org> wrote:

> On Tue, Apr 14, 2026 at 4:51 PM Adam Koszek via TUHS <tuhs at tuhs.org> wrote:
> > 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?
> 
> I can't speak to historical examples, but I can say that at work we've
> taken a big magnet and pointed it at traces on our boards to induce
> errors to see how software handles them.
> 
>         - Dan C.
> 

Literature states that the initial work on the filesystem was all simulated in GECOS on the 635.  How deeply they simulated potential hardware errors in the midst of that I couldn't say, but my understanding is there is a long tradition of simulation in UNIX development, but I don't know how much this implies direct instrumentation of test cases vs. experimentation on the more abstract design elements.

- Matt G.