Testimony is Evidence

[Court Jester]

To declare something as evidence takes a whole canopy of references, not just eye-witness accounts. Stuff like repeatable observations/experiments, several independent observers, blind testing and so on.

You are confusing the word evidence with the word proof.

They're kind of one in the same there buddy.

Proof http://www.dictionary.com/browse/proof?s=t
noun
1. evidence sufficient to establish a thing as true, or to produce belief in its truth.

Evidence http://www.dictionary.com/browse/evidence?s=t
noun
1. that which tends to prove or disprove something; ground for belief; proof.