- test_create_printer_persisted: POST /printers + GET /printers
- test_create_printer_duplex/color_mode/paper_size/collate: field persistence
- test_create_client: POST /clients + GET /clients
- test_printer_grouped_by_client: client group heading in list
- test_create_printer_missing_name/invalid_ip: validation 400s
- test_delete_printer: DELETE /printers/{id} removes record