if the billing data was incorrect and needs to be rebuilt, we should
remove old rows. Previously we were only upserting new rows, but old
no-longer-relevant rows were staying in the database. This commit
makes the flask command remove *all* rows for that service and day,
before inserting the rows from the original notification data after.
This commit doesn't change the existing nightly task, nor does it
change the upsert that happens upon viewing the usage page. In normal
usage, there should never be a case where the number of billable units
for a rate decreases. It should only ever increase, thus, never need to
be deleted
Added the letter_rate table to the list of tables which does not get
deleted after each test run and changed the tests to use the real letter
rates.
Also removed the letter rate DAO since this was only being used in
tests, so was no longer needed.
- Change the usage queries to a union so that billing_units is correct for all notification types. Removing the business logic from the schema.
- Added tests for different fragment counts, rates and sheet counts.
This was because the rate_multiplier was being added as 1 and 1.0 which was not resolving to the same.
This updates the table to use Integrer.
Also changed the logging for the task.
The timezone added is that of the database - locally a db will get timezone=GB, but the servers are using UTC (which is right)
This date is trucated to month, and is BST, here time and timezone is irrelevant.
