The phrase "attest when it" is not correct and does not form a complete thought in written English.
It may be intended to express a condition or situation where someone is asked to confirm or verify something at a specific time or event.
Example: "I can only attest when it is necessary for the legal proceedings."
Alternatives: "confirm when it" or "verify when it".
AS thousands of passengers who were caught up in the latest bout of snowstorms along the East Coast can attest, when weather disrupts the system, travelers are basically on their own.
Gay or lesbian-themed advertising is still a relatively new marketing realm, and as these commercials attest, when same-sex themes are included in mainstream commercials, they're usually intended for comic effect.
As many people can attest, an animal is often at its most dangerous when it's sick, wounded or afraid.
It is true that the whole elaborate apparatus seems like a phantasm and few can attest to experiencing the intrusion, because when it happens it is as painless as a mosquito bite.
As a party scene between two young musicians, who play a drinking game while trying to outdo each other in the expert performance of orchestral excerpts, accurately attests, classical musicians are no slouches when it comes to the downing of grape and grain.
As a grateful alumna, I can attest that Oberlin focuses on the very best possible experience for its students even when it's tough.
He may be right about Christianity, but when it comes to Judaism, I can attest that he's wrong: our mothers make us feel guilty.
"When it comes time for the auditors to attest, they are going to be very conservative," Mr. Rosner said.
The town's remains attest to Carthaginian settlement before it came under Roman rule, when it functioned as a trading centre known as Tacapae.
As any cell phone user can attest, small size and longevity seem to be mutually exclusive when it comes to batteries.
