Once I was asked in an interview (I was the interviewer!) What do you do in situations where the customers don’t want you to write test cases, or they want you to deprioritize the activity of writing test cases.
My answer was, the customer gets such ideas if you show test cases as a separate activity; if testing becomes an inherent part of your development workflow, then one cannot tear them apart. This is where methodologies like TDD help, delivering features mean delivering features with tests, they should not be two different things. Teams should not create stickies on boards or issues in Jira dedicated to unit testing.