I'm not very familiar with protobuf, but in searching, repeated field seems to have list- or set-like semantics, so yeah, I'd parse the value into a list or a set and compare it to a list or a set.
If you were going to work with protocol buffers frequently you'd probably quickly find yourself doing this over and over, and would then create the aforementioned `assertThat(expected).containsInAnyOrder(foo,bar,baz);`.
