  We study the coboundary expansion property of product codes called product
expansion, which played a key role in all recent constructions of good qLDPC
codes. It was shown before that this property is equivalent to robust
testability and agreement testability for products of two codes with linear
distance. First, we show that robust testability for product of many codes with
linear distance is equivalent to agreement testability. Second, we provide an
example of product of three codes with linear distance which is robustly
testable but not product expanding.
