What is with this test? For Dictionary and SmallDictionary it gives an error. Please fix... Cheers, Adrian testDo2 "dc: Bad test, it assumes that a new instance of #speciesClass allows addition with #add:. This is not the case of Interval for which species is Array." | res | res := self speciesClass new. self collection do: [:each | res add: each class]. self assert: res = self result. ___________________ http://www.adrian-lienhard.ch/