The popularity of diet fads is a 'testimony to' the fact that people want a quick fix for their health and weight problems.
It is 'testimony to' her courage and persistence that she worked for so long in the face of such adversity.
There were contradictions in her 'testimony'.
(..) at a hospital which serves people. In your professional medical opinion, was Willie Santiago poisoned? We renew our objection to Commander Stone's testimony... and ask that it be stricken from the record. We further ask the court members to lend no weight to this witness's testimony. (..)1992 A Few Good Men
(..) to call its first witness? If it please the court, the government calls Mr. R.C. McGuire. Mr. McGuire, would you raise your right hand, please? Do you solemnly swear that the testimony you give this general court-martial... will be the truth, the whole truth and nothing but the truth? - I do. (..)1992 A Few Good Men