Add tests for barcode scanner hook

src/hooks/__tests__/useBarcodeScanner.test.tsx

@@ -0,0 +1,128 @@
+import { renderHook, waitFor } from '@testing-library/react';
+import { describe, it, beforeEach, afterEach, expect, vi, type MockInstance } from 'vitest';
+import { useBarcodeScanner } from '../useBarcodeScanner';
+
+const decodeFromVideoDevice = vi.fn();
+
+vi.mock('@zxing/browser', () => ({
+  BrowserMultiFormatReader: vi.fn().mockImplementation(() => ({
+    decodeFromVideoDevice,
+  })),
+}));
+
+declare global {
+  interface Window {
+    BarcodeDetector?: new () => { detect: (source: ImageBitmapSource) => Promise<{ rawValue: string }[]> };
+  }
+}
+
+const createMediaStream = (stopSpy: MockInstance = vi.fn()) => {
+  const track = { stop: stopSpy } as MediaStreamTrack;
+  return {
+    getTracks: vi.fn(() => [track]),
+    getVideoTracks: vi.fn(() => [track]),
+  } as unknown as MediaStream;
+};
+
+const createVideoElement = () => {
+  let srcObject: MediaStream | null = null;
+  return {
+    play: vi.fn(() => Promise.resolve()),
+    get srcObject() {
+      return srcObject;
+    },
+    set srcObject(value: MediaStream | null) {
+      srcObject = value;
+    },
+  } as unknown as HTMLVideoElement;
+};
+
+beforeEach(() => {
+  decodeFromVideoDevice.mockReset();
+  (globalThis as unknown as { createImageBitmap: typeof createImageBitmap }).createImageBitmap = vi
+    .fn()
+    .mockResolvedValue({} as ImageBitmap);
+  Object.assign(navigator, {
+    mediaDevices: {
+      getUserMedia: vi.fn(),
+    },
+  });
+});
+
+afterEach(() => {
+  vi.clearAllMocks();
+  delete (window as Window & { BarcodeDetector?: unknown }).BarcodeDetector;
+});
+
+describe('useBarcodeScanner', () => {
+  it('uses native BarcodeDetector when available and sets the detected code', async () => {
+    const trackStop = vi.fn();
+    const stream = createMediaStream(trackStop);
+    (navigator.mediaDevices.getUserMedia as unknown as vi.Mock).mockResolvedValue(stream);
+
+    class MockBarcodeDetector {
+      detect = vi.fn(async () => [{ rawValue: 'NATIVE-123' }]);
+    }
+
+    (window as Window).BarcodeDetector = MockBarcodeDetector;
+    const videoElement = createVideoElement();
+
+    const { result, unmount } = renderHook(() => {
+      const hook = useBarcodeScanner();
+      hook.videoRef.current = videoElement;
+      return hook;
+    });
+
+    await waitFor(() => expect(result.current.result.code).toBe('NATIVE-123'));
+
+    expect(navigator.mediaDevices.getUserMedia).toHaveBeenCalledWith({ video: { facingMode: 'environment' } });
+
+    unmount();
+    expect(trackStop).toHaveBeenCalled();
+  });
+
+  it('falls back to BrowserMultiFormatReader and returns decoded text', async () => {
+    delete (window as Window).BarcodeDetector;
+    const stopControls = vi.fn();
+
+    decodeFromVideoDevice.mockImplementation(async (_deviceId, _video, callback) => {
+      callback({ getText: () => 'FALLBACK-789' } as unknown as { getText: () => string });
+      return { stop: stopControls };
+    });
+
+    const videoElement = createVideoElement();
+
+    const { result, unmount } = renderHook(() => {
+      const hook = useBarcodeScanner();
+      hook.videoRef.current = videoElement;
+      return hook;
+    });
+
+    await waitFor(() => {
+      expect(decodeFromVideoDevice).toHaveBeenCalled();
+      expect(result.current.result.code).toBe('FALLBACK-789');
+    });
+
+    unmount();
+    expect(stopControls).toHaveBeenCalled();
+  });
+
+  it('surfaces errors encountered while starting the scanner', async () => {
+    (navigator.mediaDevices.getUserMedia as unknown as vi.Mock).mockRejectedValue(new Error('Camera denied'));
+
+    class MockBarcodeDetector {
+      detect = vi.fn(async () => []);
+    }
+
+    (window as Window).BarcodeDetector = MockBarcodeDetector;
+    const videoElement = createVideoElement();
+
+    const { result } = renderHook(() => {
+      const hook = useBarcodeScanner();
+      hook.videoRef.current = videoElement;
+      return hook;
+    });
+
+    await waitFor(() => expect(result.current.result.error).toBe('Camera denied'));
+  });
+});