It's pretty common outside of startups and Big Tech. My boss at my first job told me specifically to "not waste time" writing tests, which I thought was insane

It's pretty common outside of startups and Big Tech. My boss at my first job told me specifically to "not waste time" writing tests, which I thought was insane and I ignored him since the were having me write a system for charging subscriptions. I'm fine with not writing tests so long as I'm not held responsible when something unexpected happens. Unfortunately for you, they are making you responsible for your own code and have no form of code review. If you can, you ought to write tests anyway as a part of your work, even if it's just a handful of end-to-end tests to ensure you don't cause anything catastrophic. And if they ask you for an explanation, just tell them that having those tests in place helps you get more work done and not waste time. There's a chance they're going to be irrational and opt to run their own software into the ground long-term. If they tell you not to write tests, I'd suggest continue working there until you've held your position for a year and, in the meantime, keep looking out for better opportunities. The reason I say that is because if you adopt their cowboy-coding culture long enough, it will sink in with you and it will be harder for you to adopt best practices at your next employer.