Unit tests was just an example. The issue is deeper than that.
When I ask a question in a job interview, it’s because I want to learn something about the company, because I want to know whether its corporate culture and its philosophy of how to run a software shop are in sync with how I want to work. If significant questions get the “it depends” answer, I take it as a sign that either the place is so chaotic that it doesn’t have a corporate culture, or that I won’t know what culture I will work in until I find out who my manager is.
But that's the case at any organization of non-trivial (> about 10 people) size. You can't enforce uniformity - if you do, you end up with a sicker system than if you'd just let everyone do the wrong thing.
One of the key signals I use to judge someone's intelligence is their willingness to say "It depends." Because that demonstrates their comfort with ambiguity, their ability to see distinctions in circumstances, and their confidence in being able to make sense of unfamiliar surroundings. All of these are absolutely essential in doing high-level creative work, where there's no roadmap of best practices because nobody's done it before.
It's great that you ask the question, but if you're looking for a specific answer, you're doing it wrong. You should then be able to drill down into "Depends on what?", and then if you can have a sensible conversation based on that, you've probably found someone worth working with.
In the cases I’m thinking of, “depends on what?” was met with more vagueness, or, in one case, “depends on what the client wants”. (This was at one of those companies whose business model involves a very small core product and a lot of per-customer consulting work to enhance it. Which is a perfectly respectable way to run a company, but the core-to-consulting ratio was too low for my taste.)
"If significant questions get the “it depends” answer, I take it as a sign that either the place is so chaotic that it doesn’t have a corporate culture, or that I won’t know what culture I will work in until I find out who my manager is."
Or, you know, it means "it depends". Because sometimes, it depends on the circumstance. As they say, the exceptions make the rule.
The larger point here is that if you go into an interview prepared to dump on a company because they're not absolutists about your particular favorite development philosophy, you shouldn't be surprised if you don't get the job. And nearly every company is going to have something that they're letting slack in order to keep the lights on.
So maybe not having unit testing is a deal-breaker for you. If so, fine. Don't work for companies that don't unit test. But I hope your list of deal-breakers is short.
When I ask a question in a job interview, it’s because I want to learn something about the company, because I want to know whether its corporate culture and its philosophy of how to run a software shop are in sync with how I want to work. If significant questions get the “it depends” answer, I take it as a sign that either the place is so chaotic that it doesn’t have a corporate culture, or that I won’t know what culture I will work in until I find out who my manager is.