Todos los siguientes casos deberian dar OK
Context C
invariantUnion0 : Sequence{'a', 'b', 'a'}->union(Sequence{'b', 'c'})=Sequence{'a', 'b', 'a', 'b', 'c'}
FAIL
Context C
invariantUnion0a : Bag{'a', 'b', 'a'}->union(Bag{'b', 'c'})=Bag{'a', 'b', 'a', 'b', 'c'}
OK
Context C
invariantUnion0b : Bag{'a', 'b', 'a'}->union(Set{'b', 'c'})=Bag{'b', 'c', 'a', 'b', 'a'}
OK
Context C
invariantUnion0c : OrderedSet{'a', 'b', 'a'}->union(Bag{'b', 'c'})=Bag{'a', 'c', 'b', 'b'}
FAIL
Context C
invariantUnion0d : OrderedSet{'a', 'b', 'a'}->union(Set{'b', 'c'})=Set{'a', 'c', 'b'}
FAIL
Context C
invariantUnion0e : Set{'a', 'b', 'a'}->union(Bag{'b', 'c'})=Bag{'a', 'c', 'b', 'b'}
FAIL
Context C
invariantUnion0f : Set{'a', 'b', 'a'}->union(Set{'b', 'c'})=Set{'a', 'c', 'b'}
FAIL