isn't it, though?
- A testament is a will or if you will: a covenant/promise
- A testimony is proof/evidence
So all those who say e.g. "the response of the emergency services was a testament to their training, compassion blah blah blah"
...should be saying "the response of the emergency services was a testimony to their training...."
Sorry about the poe-faced example, but it's often used in this context or of people being brave - which makes you feel even more of a prick for coming over all pedantic.
I was pulled up by a lecturer aged 19 on this and HAVE NEVER FORGOTTEN and inwardly cringe when I hear this on practically every news bulletin ever. And I need to relax.