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Comment by balderdash | Hacker News Reader

We have an embedded system in one of product offerings that was largely developed using a bunch of “antiquated” technologies (over the past twenty years) and over the past year the two software devs that maintained it have retired. This normally would have big problem, but the entire codebase was re-written, documented, and modernized in a matter of about 3 months (for about $20k in tokens, and a mid level developer spending 50% of their time on it over that period). So it doesn’t surprise me to think a company like Cisco has piles of situations like this.

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That's really interesting.

What have been achieved using this port?

And how did you make sure the port is correct?

> And how did you make sure the port is correct?

I'd ask "did you make sure the port is correct?"

Curious, why did it take 3 months and not a few days? Honest question, just curious about what is consuming all the time in a project like this?

Due diligence?

What’s that? Is there an MCP server for it?

Just add “test everything”, “this is mission critical” and “make no mistakes” to the prompt.

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Need to keep the bubble alive one more day

I didn’t work on it, but from afar it was a mission critical in-production system (with multiple modules / services like data collection, interpretation, visualization, etc) with minimal documentation and numerous other software dependencies. A lot of the work was understanding exactly how it worked and what/how it interacted with other systems. “Re-writing it” want the hard part, making sure nothing downstream broke was a lot of the work.

Every time something like this has been done on my company I follow up with the question: did anyone watched the code to see if the business logic is the same between the two versions? The answer is: but but but automated testing.

Followup question: did anyone read the automated test suite?

Silence.

The software rewrite is shelved.

Yup. And its always garbage as result

Not if you have a good harness. Docs and tests first

Honest question: does that even remotely matter, or is it an outdated prior? All software has bugs.

The goal and objective is to deliver value for your user/customers; to the speed, reliability, and assurance requirements your market segment expects.

All software has bugs, but right now you have a legacy product in production that works, then you have a rewrite that nobody tested. Do you accepted the risk to yolo it?

Sometimes the risk is acceptable, sometimes it's not.

> to the speed, reliability, and assurance requirements your market segment expects.

I suspect that the average Cisco customer expects a bit more stability than $RANDOM_SAAS.

I worked with Cisco products over 30 years, I don't expect much from experience.

Why do people doing a rewrite need to have read the tests?

If you have good test coverage, and the tests are reliable, then what's the problem?

If your engineering culture is bad already and you don't have good test coverage or they're flaky or whatever then that is different. If that is the case, it is probably from smart-ass attitudes like yours asking these "clever" rhetorical questions to derail people trying to improve things that led it to be like that. Do everyone a favour and keep your mouth shut and let people fix things.

The tests aren't reliable if the entire codebase was rewritten, including the tests, and then nobody read the tests.

> [if] the tests are reliable

Reading the tests is meant to check that.

also take the money saved on engineering and just run two systems in parallel for a year

> did anyone watched the code to see if the business logic is the same between the two versions?

Why not just ask the coding assistant?

Ok but what’s the alternative? Owning a piece of software nobody understands or knows how to maintain?

I’ll take the system written in a language that people can maintain and fix

The alternative is spending money on AI and spending money on someone reviewing the code. But the last one is an hard sell

The self-driving bus factor.

Every time somebody rewrote code in my company, my questions were more on the line of "why did you preserve all the known bugs and incoherences?"

The answer is always that the rewrite was bug-compatible on purpose, the bugs were to be fixed later on the more tractable system. Every time development was abandoned right away, because there was no gain in using the new system.

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