Cost includes the impact on further tests and maintenance.
The cost of testing and debugging increases as you go down the development/release cycle.
If you have unit tests then that helps integration tests (less issues, easier to investigate), system tests, etc. all the way down to dealing with bug reports from the field.
> but most units are not that complex and should not require unit tests.
> If you have unit tests then that helps integration tests (less issues, easier to investigate), system tests, etc. all the way down to dealing with bug reports from the field.
Not in my experience. I don't see how a unit tests helps me with bugs that show up in the field. If it shows up in the field, something should've caught it, which means testing failed.
The cost of testing and debugging increases as you go down the development/release cycle.
If you have unit tests then that helps integration tests (less issues, easier to investigate), system tests, etc. all the way down to dealing with bug reports from the field.
> but most units are not that complex and should not require unit tests.
That is a very bold claim...