There is no such thing as a "billing unit". The data this field
contained was also a confusing mixture of two types:
- For emails and letters, it was just "notifications_sent".
- For SMS, it was the "chargeable_units" (billable * multiplier).
This replaces the single, ambiguous "billing_units" field with
"chargeable_units" and "notifications_sent" in both usage APIs.
Once Admin is using them we can remove the old field.
We were using the Draft4Validator in one place, so this updates it to
the Draft7Validator instead.
The schemas were mostly using draft 4 of the JSON schema, though there
were a couple of schemas that were already of version 7. This updates
them all to version 7, which is the latest version fully supported by
the jsonschema Python package. There are some breaking changes in the
newer version of the schema, but I could not see anywhere would these
affect us. Some of these schemas were not valid in version 4, but are
now valid in version 7 because `"required": []` was not valid in earlier
versions.
We were already returning the month, notification_type, billing_units
and rate from the /monthly-usage billing endpoint. This adds in the
postage too so that we can display postage details on the usage page of
admin.
- 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.
- moved get_current_financial_year_start_year from service.utils to dao.date_utils
- Moved logic for data persistence from rest to dao when updating records in db
