[barrkel]

Unit tests on code that has no dependencies (and I mean no dependencies, neither injected nor direct) is great.

Unit tests on code with dependencies (whether injected so that they can be mocked, or directly referenced so that they end up more like mini integration tests) are less excellent. They're brittle, inhibit refactoring, and either don't test as much as you think they do (if mocking dependencies) or are slow (if not mocking).

The further up the testing pyramid you go, the less work it is to refactor things, because you don't need to rewrite as many tests. OTOH test are more complex to write and take longer to run.

And now I get to my point: I don't think the blanket statement of "your largest set of test should be ... unit testst that run quickly" is well-founded. There are trade-offs, and they shouldn't be trivially waved aside.