Are you sure you don't mean evidence-free testimony? If I testify that bigfoot sleeps under my bed is that evidence of bigfoot?
"Evidence" is a peculiar word and often misunderstood.
Things, (oh say, like a knife or a gun) is not evidence for sake that there is something. Things, when used to show or demonstate something can then be considered evidence. Again, to show or demonstrate something else.
There is more, and this is often troubling for some people. If I take a gun and shoot your wife (while you're on a date with your girlfriend), and if then I later break into your home and place that gun I fired and place it in your bedroom closet, the gun that I put there that the police later find will be considered evidence, and it will be used to show that you killed your wife.
This is where people object and say that it's merely evidence of a gun, but no, it's evidence being used to show that you killed your wife. It does not have to successfully show or demonstrate what it's being used to show or demonstrate.
So (believe it or not) yes, your testimony that Bigfoot sleeps under your bed is evidence, not because you're saying it per se, but because you're attempting to make the case that he does. Furthermore, that what you're saying may be false does not render the claim non-evidentiary.