[bluejekyll]

> it won't provide 100% code coverage.

Yeah. 100% coverage is BS, again I go back to proof of quality.

> because the find ever-more subtle bugs

Well, yes and no. Yes integration tests are important for finding subtle bugs between different components of a larger system. No, bc an over-reliance on these instead of proper unit-testing, you end up with code bloat in your integration tests, and a maintenance nightmare because the tests are more complex. On top of that because you have so many integration tests It becomes unclear when the integration test is testing a valid API construct, vs something internal, making it very difficult to refactor code because you don't know what's expected API response vs some odd internal bug that you had to test for bc you didn't have a good unit test for the internals.