Adding test for ellipsis homogenisation

[robinlmp]

I'm less confident about this. I've not written or done any tests to date so I've largely approached it by trying to match the pattern of existing tests. Reasonably confident I've got it in the right file and right place. Properly learning about testing clearly needs to be on my list of to dos. Saying that, fingers crossed on this one.

[Carrione]

Related to #215

[twostraws]

This looks fine to me – great job!