Comment by avensec

Your point is valid, and some of the dialog in the replies to your comment is also valid. So, I'm just responding to the root of the dialog. What architectures are you working with that suggest higher integration test strategies?

I'd suggest that the balance between Unit Test(s) and Integration Test(s) is a trade-off and depends on the architecture/shape of the System Under Test.

Example: I agree with your assertion that I can get "90%+ coverage" of Units at an integration test layer. However, the underlying system would suggest if I would guide my teams to follow this pattern. In my current stack, the number of faulty service boundaries means that, while an integration test will provide good coverage, the overhead of debugging the root cause of an integration failure creates a significant burden. So, I recommend more unit testing, as the failing behaviors can be identified directly.

And, if I were working at a company with better underlying architecture and service boundaries, I'd be pointing them toward a higher rate of integration testing.

So, re: Kent Dodds "we write tests for confidence and understanding." What layer we write tests at for confidence and understanding really depends on the underlying architectures.