I don't really mention tests to my management. To me, they are just part of coding. My coworkers don't mind, they are happy when maintaining or changing my code that they have tests for support.
I've adopted your same approach. I don't mention testing, but I'll be damned if I'll ever write a piece of code without it.
The light-bulb moment for me was when I realized that testing happens one way or another. Either you're in the console manually setting up and running everything... or you could just write a program (a test) to do the same thing for you. Once I realized that, I never looked back!
What I'm saying is if we accept the company's viewpoint as truth -- I don't -- then you'd just be writing code and handing it over. No testing. No execution. No nothing. But if you have time to manually test the code, then it sounds like you have time to write automated tests.
Now, I'm with you, these tests aren't going to be beautiful or well-factored, but they'll be helpful to you, right? That way you don't have to manually test the code over and over again.
On the other side of the coin, I've taken on the practice of including time necessary for testing in my estimates (as an employee and contractor). If a manager doesn't want to accept that, then they can fire me, because that manager is fully incompetent -- no ifs ands or buts. As a professional, I need to operate with a test-driven approach. It's the only way to deliver complex systems with confidence.
Testing happens one way or another.
This. Just yesterday, I was asked by an interviewer at a Startup. "How do you test your code? Do you write tests? What's your familiarity with TDD."
My answer: "I prefer to do a test driven approach. However, none of the companies I worked for allocated time for writing tests in the sprint, so I have not been able to actually do this in practice. I usually debug my code and run it through all the happy path and edge cases."
Was bitten once very early in my career just like OP, and decided to only write tests after initial coding, if there was time left. Most (not all) Companies expect you to do TDD, but never allocate time for it in the estimation. So I've made it a point to ask the PM if there was time allowed for writing tests in the estimate, and if they say something like "Oh no we don't have time for that" I don't do it.