In most cases especially for important code paths I agree. There is a case where I think it is justifiable to not write a single test: Startups. Specifically p

In most cases especially for important code paths I agree. There is a case where I think it is justifiable to not write a single test: Startups. Specifically pre-seed & seed round funded I think are allowed to skip the majority of tests - however critical paths, especially those that are important to customers (i.e. transactions) must be tested. By the time you have built out that mvp and have a few customers then you should transition to writing more tests. And as the number of engineers, scope, or complexity grows you need to add tests.