Perryn Fowler has a few words
of wisdom to share on what can and cannot be tested. I especially like
his closing remark.
His remarks are short, so I have reproduced them here in full.
some things you just can’t test
Rubbish. Think harder.
Of course some things are very difficult to test, and in some cases the
effort is not worth it when compared to the amount of risk it would
mitigate - but that is a business decision rather than a purely technical
one.
You can make this decision a lot easier by not putting important
behaviour in things that are hard to test
