Date fields can now be updated and their values retrieved. So now I have added a button that retrieves the range of the date field and updates the historical view in response to them.
This required some big overhauls. The view model no longer takes records. It only takes the date that it is responsible for, and it will ask the database for records pertaining to that date. This means that once the view model has saved all of its records, it can simply reload those records from the database. This has the effect that as soon as the user moves from DayEdit back to DayDetail, all of the interesting information has been repopulated.
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.
I've created the DaySummary structure and set up a list view to go into
the historical view. One hard-coded date is visible as a placeholder to
start filling things into the day summary.
