Use 'attest' when you want to show something is definitely true or real through evidence. The numerous awards on her wall attest to her exceptional skill.
Pro Tip 2/3
Personal Experience
'Attest' can be used when someone's personal experience confirms something. I can attest to the comfort of these chairs, having sat on them myself.
Pro Tip 3/3
Subject Expertise
An expert may 'attest' to facts within their field, adding credibility. The scientist attested to the urgency of climate change.