I'm not disagreeing with you; I really like both of your points however, I have two problems with assertions. Let's say the assertion is inside a function e.g.:

I'm not disagreeing with you; I really like both of your points however, I have two problems with assertions. Let's say the assertion is inside a function e.g.: void function adjust_fan_control(uint8_t fan_speed) { assert(0 != fan_speed); ... // some complicated code here } What if the adjust_fan_control function isn't necessarily called for a given run of the program? Then you don't know if you actually tested that assertion, that is for all callers of function X, you don't know if all those callers are calling X correctly if you only rely on the above. Of course I'm not trying to suggest that you're arguing for assertions to the exclusion of tests, just pointing this out. The second problem I have with them is in embedded systems. I'm heavily in favor of putting assertions (which are then omitted in prod builds, or instead of looping the LED blink routine they map to a soft reset if fail) inside functions in embedded systems. However, if I have very limited I/O, specifically, I don't have the ability to log when/where an assert was hit, all I know is that an assert was hit because the LED pattern goes to 'blink really fast like this indefinitely which means an assert failed'. If I have a lot of asserts, that doesn't really tell me anything. On the other hand, if I have unit tests, and my mocks assert, and I can run the unit tests on a simulator or heavily instrumented system, then I know which assert failed in what function and who called that function. The point is I can't do that (or I don't know how) without the tests. Edit: formatting.