hello, two bugs: Collection>#union: and Collection>#collectUnion: the first pb is where the receiver is a set, and the second one is that (#(1 2 3) union: #(1 2 3 4))-->#(1 2 3 4), but (#(#(1 2) #(2 3) #(3 4)) collectUnion: [:each])-->#(1 2 2 3 3 4). I have added some new asserts inside CollectionTest>>#testCollectUnion (actually there is two red tests in this class) and published a new version of CodeFooDevelopment.
best wishes, hani