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'.
(..) - Professor. - Yeah. Igor Karkaroff, you have been brought from Azkaban at your own request... ...to present evidence to this council. Should your testimony prove consequential... ...council may be prepared to order your immediate release. Until such time, you remain in the eyes (..)2005 Harry Potter and the Goblet of Fire