Maybe add tests for:
 * Importing the same CSV file twice should not result in double the same department returning twice from the search endpoint.
 * Scoping of departments to tenants
 * Clashes of department ids. We should probably prefix the department IDs with the tenant alias. Maybe even make it `d:<tenantAlias>:<department ID>`
 * When you've imported the same CSV for two different tenants you should be able to search for a department on each tenant as they should be distinct given the above ID construction