This simplifies, though not as much as I was hoping, the patterns for accessing data along strict type patterns. I may see better results once I'm getting the Time/Distance views working.
Step and weight records may be presented in any order. Any test that
tries to enforce that one gets presented before teh other can't cannot
succeed. So, I've removed that test and instead put in a warning that
will appear when the view model gets loaded.
DayDetailViewModel needs testing. I've worked out an improved API, and a set of tests to go along with it, and those can be made more easily with a mockable RecordProvider. So, in addition to stubbing out a bunch of tests, I've also created RecordProvider, mocked it, and implemented it for App.
This is preparatory work. Having the view model directly retrieve data both adds a degree of symmetry (it both gets data from and sends data to the app) and makes it possible for the view model to refresh itself when needing to revert data or after saving data.
