Uhm… You are right. The reason is that in the array tests there are not stored the objects Test themselves, but just pointers to them, so there is a double indirection (because they are mutable, which I didn’t notice).
The following works, but seem extremely fragile, so there must be a better solution:
p = Base.unsafe_convert(Ptr{Ptr{Test}}, pointer(tests, 1))
unsafe_load(unsafe_load(p))
Edit
This works as well and is a bit cleaner:
p = Base.unsafe_convert(Ptr{Test}, Ref(tests, 1))
unsafe_load(p)