That end to end tests for critical business functions will save your ass the moment you, your team, or your test suite fails to spot a bug. I once added a line

That end to end tests for critical business functions will save your ass the moment you, your team, or your test suite fails to spot a bug. I once added a line of code that did not execute in test environments because it involved a request to hosts that were only available on staging and production. So the tests were obviously fine but shit went south in production.