Does anyone know if there's any way of treating DAX functions like mocked functions so they can spit out different values during testing? In particular it would be useful to specify the value returned by USERPRINCIPALNAME/USERNAME in desktop when you don't want to see 'your own' row limited set.
I'd imagine this would be a broadly useful feature, since USERPRINCIPALNAME is used in the overwhelming majority of RLS cases, and I would have thought it's quite a common scenario where a dataset developer doesn't exist in a business dataset (because they work in a separate function). When this happens the developer gets no rows back when ideally they would want to see a typical use case.
At the moment, the workaround is to comment out calls to the USERPRINCIPALNAME function and put a line below with a hard coded string. This isn't ideal given that the DAX editor in the manage roles dialogue isn't very good (can't indent, narrow space so you get a lot of visually confusing text wraps), and this could lead to testing code ending up in production.
