Add targeted Vitest coverage

tests/useBarcodeScanner.spec.tsx

@@ -0,0 +1,57 @@
+import { renderHook, waitFor } from '@testing-library/react';
+import { describe, expect, test, vi, beforeEach, afterEach } from 'vitest';
+
+vi.mock('@zxing/browser', () => {
+  class MockReader {
+    decodeFromVideoDevice = vi.fn(async (_device: any, _video: any, callback: any) => {
+      callback({ getText: () => 'decoded-fallback' } as any);
+      return { stop: vi.fn() } as any;
+    });
+  }
+  return { BrowserMultiFormatReader: MockReader };
+});
+
+describe('useBarcodeScanner', () => {
+  beforeEach(() => {
+    vi.resetModules();
+    vi.clearAllMocks();
+    (globalThis as any).BarcodeDetector = undefined;
+  });
+
+  afterEach(() => {
+    delete (globalThis as any).BarcodeDetector;
+  });
+
+  test('falls back to ZXing reader when BarcodeDetector is unavailable', async () => {
+    const { useBarcodeScanner } = await import('../src/hooks/useBarcodeScanner');
+    const { result } = renderHook(() => useBarcodeScanner());
+    result.current.videoRef.current = document.createElement('video');
+
+    await waitFor(() => expect(result.current.result.code).toBe('decoded-fallback'));
+  });
+
+  test('uses BarcodeDetector when available', async () => {
+    const detect = vi.fn().mockResolvedValue([{ rawValue: 'detected-code' }]);
+    class MockBarcodeDetector {
+      detect = detect;
+    }
+    (globalThis as any).BarcodeDetector = MockBarcodeDetector as any;
+
+    const play = vi.fn().mockResolvedValue(undefined);
+    const getVideoTracks = vi.fn().mockReturnValue([{ stop: vi.fn() }]);
+    const stream = { getVideoTracks } as any;
+    navigator.mediaDevices = {
+      getUserMedia: vi.fn().mockResolvedValue(stream),
+    } as any;
+    (globalThis as any).createImageBitmap = vi.fn().mockResolvedValue({});
+
+    const { useBarcodeScanner } = await import('../src/hooks/useBarcodeScanner');
+    const { result } = renderHook(() => useBarcodeScanner());
+    const video = document.createElement('video');
+    Object.defineProperty(video, 'play', { value: play });
+    result.current.videoRef.current = video;
+
+    await waitFor(() => expect(result.current.result.code).toBe('detected-code'));
+    expect(detect).toHaveBeenCalled();
+  });
+});