https://en.wikipedia.org/wiki/S-II

"First all-up S-II stage, assembled between 1963 and 1965. Completed several engine tests at the Mississippi Test Facility (now the Stennis Space Center). Destroyed by accidental LH2 tank overpressurization during pressure testing May 28, 1966[7][6]"

and

"Destroyed in test stand September 29, 1965"

Also described here: http://heroicrelics.org/ussrc/s-ii/index.html

"The S-II program was beset with problems and delays. NASA had planned on North American making an S-II stage, S-II-D, for dynamic testing but the order for that stage was cancelled in early 1965 in favor of using the structural static test stage, S-II-S, as a combined static/dynamic test stage; that stage was renamed to S-II-S/D. Unfortunately, the S-II-S/D stage was destroyed during testing, leaving S-II-F to take on the added role of dynamic testing and being redesignated as S-II-F/D."

I though all of the Saturn V stages were destroyed during testing at least once but it looks like I remembered it wrong. :)

No one has ever built a plane, or even a car without breakage during testing. The very idea is absurd. There's a whole profession called "test pilot".

I don't know why anyone would suggest otherwise.

I'm sure there are links aplenty, but the absurd suggestion here would be building a rocket and having zero incidents of failure. That beyond weird. That's what needs a "do you have a link" question.