I'm a Google Developer Expert in Dart and Flutter (one of 12 in North America). I have 45 years of experience with backend, web, mobile, devops, and training.
Well-known software developer specializing in large-scale database-driven web sites. Usually I use Perl. I speak at too many conferences. https://allaroundtheworld.fr/
My brief way of saying this is "if your tests are hard (or impossible) to write, you probably need a refactoring or two or three..."
Absolutely! I should write a post about that: tests that are hard to write are often a code smell.