nearle_pos/test/unit/fleet_identity_test.dart

import 'package:flutter_test/flutter_test.dart';
import 'package:nearle_pos/core/config/sync_config.dart';
import 'package:nearle_pos/core/utils/formatters.dart';
import 'package:nearle_pos/data/datasources/local_store.dart';
import 'package:nearle_pos/data/datasources/seed_data.dart';
import 'package:nearle_pos/data/local/app_database.dart';
import 'package:nearle_pos/data/local/terminal_identity.dart';
import 'package:nearle_pos/data/repositories/customer_repository_impl.dart';
import 'package:nearle_pos/data/repositories/product_repository_impl.dart';
import 'package:nearle_pos/data/repositories/transaction_repository_impl.dart';
import 'package:nearle_pos/domain/entities/cart.dart';
import 'package:nearle_pos/domain/entities/transaction.dart';
import 'package:nearle_pos/domain/usecases/checkout_sale.dart';

/// What has to hold when the same build is installed on 100 tills.
///
/// Every one of these was broken: the terminal id was the literal `TERM-01` in
/// five places, so the whole fleet shared one identity, one set of MQTT topics
/// and one invoice series.
void main() {
  late LocalStore store;

  setUpAll(() {
    LocalStore.registerSeed(
      products: SeedData.products,
      customers: SeedData.customers,
    );
  });

  setUp(() async {
    store = LocalStore.instance;
    await store.reset(withCatalogue: true);
  });

  group('identity', () {
    test('a device mints an identity on first run and keeps it', () async {
      final identityStore = TerminalIdentityStore(store.catalogue);

      final first = await identityStore.load();
      expect(first.deviceId, isNotEmpty);
      expect(first.code, startsWith('T'));

      // A second read must not re-mint. If it did, a terminal would change
      // identity on every restart and orphan the bills it had already written.
      final second = await identityStore.load();
      expect(second.deviceId, first.deviceId);
      expect(second.code, first.code);
    });

    test('two devices get different codes', () {
      // Derived from the device UUID rather than a counter, because there is no
      // shared counter to draw from — each till mints alone and offline.
      final a = TerminalIdentityStore.codeFor(
        'a1b2c3d4-0000-0000-0000-000000000000',
      );
      final b = TerminalIdentityStore.codeFor(
        '9f8e7d6c-0000-0000-0000-000000000000',
      );
      expect(a, 'TA1B2');
      expect(b, 'T9F8E');
      expect(a, isNot(b));
    });

    test('renaming keeps the device id, so history still points at the till',
        () async {
      final identityStore = TerminalIdentityStore(store.catalogue);
      final before = await identityStore.load();

      await identityStore.rename(code: 'till7', name: 'Counter 7');
      final after = await identityStore.load();

      expect(after.code, 'TILL7');
      expect(after.name, 'Counter 7');
      expect(after.deviceId, before.deviceId,
          reason: 'the machine identity must survive a re-code',);
    });

    test('the identity is loaded by the store before anything is written',
        () async {
      expect(store.isReady, isTrue);
      expect(store.terminal.deviceId, isNotEmpty);
      expect(store.terminal.code, startsWith('T'));
    });
  });

  group('invoice numbers', () {
    test('two terminals ringing their first sale do not collide', () {
      // The counter lives in each till's own database, so without the terminal
      // code every device in the fleet mints INV-2608-00001 for its first sale.
      final date = DateTime(2026, 8, 1);
      final onTillA = Formatters.invoiceNumber(1, date, terminalCode: 'TA1B2');
      final onTillB = Formatters.invoiceNumber(1, date, terminalCode: 'T9F8E');

      expect(onTillA, 'INV-2608-TA1B2-00001');
      expect(onTillA, isNot(onTillB));
    });

    test('a real sale carries this terminal\'s code', () async {
      final products = ProductRepositoryImpl(store);
      final checkout = CheckoutSale(
        productRepository: products,
        customerRepository: CustomerRepositoryImpl(store),
        transactionRepository: TransactionRepositoryImpl(store),
      );

      final milk = (await products.findByBarcode('8901234500011'))!;
      final result = await checkout(
        cart: Cart(lines: [CartLine(product: milk, quantity: 1)]),
        payments: const [
          PaymentSplit(method: PaymentMethod.cash, amount: 62, tendered: 100),
        ],
        cashierName: 'Divya',
        terminalId: store.terminal.code,
      );

      expect(result.transaction.invoiceNumber, contains(store.terminal.code));
      expect(result.transaction.terminalId, store.terminal.code);
    });
  });

  group('topics', () {
    test('two terminals in one store publish on different topics', () {
      const a = SyncConfig(storeId: 'store-01', terminalId: 'TA1B2');
      const b = SyncConfig(storeId: 'store-01', terminalId: 'T9F8E');

      expect(a.orderTopic, isNot(b.orderTopic));
      expect(a.statusTopic, isNot(b.statusTopic));
      // A shared client id would evict the other till from the broker on every
      // connect, in a loop.
      expect(a.clientId, isNot(b.clientId));
    });

    test('the catalogue topic is shared, because a price change is store-wide',
        () {
      const a = SyncConfig(storeId: 'store-01', terminalId: 'TA1B2');
      const b = SyncConfig(storeId: 'store-01', terminalId: 'T9F8E');
      expect(a.catalogueTopic, b.catalogueTopic);
    });

    test('topics translate to NATS subjects', () {
      // NATS' MQTT gateway maps / to . — this is what a JetStream consumer
      // binds to.
      const config = SyncConfig(storeId: 'store-01', terminalId: 'TA1B2');
      expect(
        SyncConfig.asNatsSubject(config.orderTopic),
        'pos.store-01.TA1B2.order',
      );
      expect(
        SyncConfig.asNatsSubject(config.statusTopic),
        'pos.store-01.TA1B2.status',
      );
    });
  });

  group('database pragmas', () {
    test('foreign keys are enforced', () async {
      final rows =
          await AppDatabase.instance.db.rawQuery('PRAGMA foreign_keys');
      expect(rows.first.values.first, 1,
          reason: 'order_items must cascade with their order',);
    });

    test('a contended lock waits instead of throwing', () async {
      // Default is 0, which surfaces at checkout as "database is locked" —
      // a failed sale with a customer standing there.
      final rows =
          await AppDatabase.instance.db.rawQuery('PRAGMA busy_timeout');
      expect(rows.first.values.first, greaterThanOrEqualTo(5000));
    });
  });
}