Enforce unique product barcodes

src/screens/ManageProductsScreen.test.tsx

@@ -1,29 +1,36 @@
 import { http, HttpResponse } from 'msw';
 import { setupServer } from 'msw/node';
 import { MemoryRouter } from 'react-router-dom';
-import { render, screen, waitFor } from '@testing-library/react';
+import { fireEvent, render, screen, waitFor, waitForElementToBeRemoved } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
-import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from 'vitest';
+import { afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi } from 'vitest';
 import { ManageProductsScreen } from './ManageProductsScreen';
 
+let mockScannedBarcode = '123456';
+const mockUseProducts = vi.fn();
+const mockUseCategories = vi.fn();
+
+const mockDb = {
+  products: {
+    add: vi.fn(),
+    update: vi.fn(),
+    delete: vi.fn(),
+    where: vi.fn(),
+  },
+};
+
 vi.mock('../hooks/dataHooks', () => ({
-  useProducts: () => [],
-  useCategories: () => [{ id: 'cat-1', name: 'Snacks', created_at: 0, updated_at: 0 }],
+  useProducts: () => mockUseProducts(),
+  useCategories: () => mockUseCategories(),
 }));
 
 vi.mock('../context/DBProvider', () => ({
-  useDatabase: () => ({
-    products: {
-      add: vi.fn(),
-      update: vi.fn(),
-      delete: vi.fn(),
-    },
-  }),
+  useDatabase: () => mockDb,
 }));
 
 vi.mock('../components/BarcodeScannerView', () => ({
   BarcodeScannerView: ({ onDetected }: { onDetected?: (code: string) => void }) => (
-    <button type="button" onClick={() => onDetected?.('123456')}>
+    <button type="button" onClick={() => onDetected?.(mockScannedBarcode)}>
       Mock Scan
     </button>
   ),
@@ -36,6 +43,18 @@ describe('ManageProductsScreen barcode lookup', () => {
   afterEach(() => server.resetHandlers());
   afterAll(() => server.close());
 
+  beforeEach(() => {
+    mockUseProducts.mockReturnValue([]);
+    mockUseCategories.mockReturnValue([{ id: 'cat-1', name: 'Snacks', created_at: 0, updated_at: 0 }]);
+    mockScannedBarcode = '123456';
+    Object.values(mockDb.products).forEach((fn) => fn.mockReset());
+    mockDb.products.where.mockImplementation(() => ({
+      equals: (value: string) => ({
+        first: () => Promise.resolve(mockUseProducts().find((product: any) => product.barcode === value)),
+      }),
+    }));
+  });
+
   it('prefills the product name after scanning a barcode', async () => {
     server.use(
       http.get('https://world.openfoodfacts.org/api/v2/product/123456.json', () =>
@@ -62,5 +81,83 @@ describe('ManageProductsScreen barcode lookup', () => {
       expect(screen.getByLabelText(/name/i)).toHaveValue('OFF Test Product');
     });
   });
+
+  it('prevents adding a product with a duplicate barcode', async () => {
+    mockUseProducts.mockReturnValue([
+      {
+        id: 'prod-1',
+        name: 'Existing Product',
+        category: 'Snacks',
+        barcode: '123456',
+        unit_type: 'unit',
+        bulk_name: 'pack',
+        archived: false,
+        created_at: 0,
+        updated_at: 0,
+      },
+    ]);
+
+    const user = userEvent.setup();
+    render(
+      <MemoryRouter>
+        <ManageProductsScreen />
+      </MemoryRouter>,
+    );
+
+    await user.type(screen.getByLabelText(/name/i), 'New Product');
+    await user.click(screen.getByRole('button', { name: /scan barcode/i }));
+    await user.click(screen.getByRole('button', { name: /mock scan/i }));
+    await waitForElementToBeRemoved(() => screen.queryByRole('dialog', { name: /scan barcode/i }));
+    await user.click(screen.getByRole('button', { name: /save product/i }));
+
+    expect(await screen.findByText(/barcode is already assigned/i)).toBeVisible();
+    expect(mockDb.products.add).not.toHaveBeenCalled();
+  });
+
+  it('prevents updating a product to use an existing barcode', async () => {
+    mockUseProducts.mockReturnValue([
+      {
+        id: 'prod-1',
+        name: 'Existing Product',
+        category: 'Snacks',
+        barcode: '123456',
+        unit_type: 'unit',
+        bulk_name: 'pack',
+        archived: false,
+        created_at: 0,
+        updated_at: 0,
+      },
+      {
+        id: 'prod-2',
+        name: 'Another Product',
+        category: 'Snacks',
+        barcode: '654321',
+        unit_type: 'unit',
+        bulk_name: 'pack',
+        archived: false,
+        created_at: 0,
+        updated_at: 0,
+      },
+    ]);
+
+    const user = userEvent.setup();
+    render(
+      <MemoryRouter>
+        <ManageProductsScreen />
+      </MemoryRouter>,
+    );
+
+    await user.click(screen.getByLabelText(/edit existing product/i));
+    const barcodeField = screen.getByLabelText(/barcode/i);
+    fireEvent.change(barcodeField, { target: { value: '654321' } });
+    expect(barcodeField).toHaveValue('654321');
+    await user.click(screen.getByLabelText(/save product/i));
+
+    await waitFor(() => {
+      expect(barcodeField).toHaveAccessibleDescription('This barcode is already assigned to another product.');
+      expect(barcodeField).toHaveAttribute('aria-invalid', 'true');
+    });
+    expect(mockDb.products.update).not.toHaveBeenCalled();
+  });
 });