Delta endpoint tests

[AntoineDao]

Would be good to add tests for new features to make sure we release a working server 😉

I'm referring to the changes made in #180.

Assigning this to you @PaulPoinet as you wrote the feature and understand it best.

PS: top tip, if you follow angular commit message style you can also trigger automated releases of the server and upgrade the version accordingly.

[AntoineDao]

So re these commits:

Are they production ready/tested/releasable commits?

I reckon we should prune them from the master branch if this is not the case as these might get released when we next commit fix/feature changes to master.

Any thoughts @PaulPoinet or @didimitrie ?