add tests for updater.ts

Covers the three checkForUpdate outcomes (null/error/available) and
the install() flow (downloadAndInstall then relaunch).

src/updater.test.ts

@@ -0,0 +1,80 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { checkForUpdate } from './updater';
+import * as storage from './storage';
+import type { Update } from '@tauri-apps/plugin-updater';
+
+vi.mock('./storage', () => ({
+  isTauri: vi.fn(),
+}));
+
+vi.mock('@tauri-apps/plugin-updater', () => ({
+  check: vi.fn(),
+}));
+
+vi.mock('@tauri-apps/api/app', () => ({
+  getVersion: vi.fn(),
+}));
+
+vi.mock('@tauri-apps/plugin-process', () => ({
+  relaunch: vi.fn(),
+}));
+
+describe('checkForUpdate', () => {
+  beforeEach(() => {
+    vi.resetAllMocks();
+    vi.spyOn(console, 'info').mockImplementation(() => {});
+    vi.spyOn(console, 'warn').mockImplementation(() => {});
+  });
+
+  it('should return null if not in Tauri', async () => {
+    vi.mocked(storage.isTauri).mockReturnValue(false);
+    const result = await checkForUpdate();
+    expect(result).toBeNull();
+  });
+
+  it('should return "error" if dynamic import or check throws', async () => {
+    vi.mocked(storage.isTauri).mockReturnValue(true);
+    const { check } = await import('@tauri-apps/plugin-updater');
+    vi.mocked(check).mockRejectedValue(new Error('Network error'));
+
+    const result = await checkForUpdate();
+    expect(result).toBe('error');
+    expect(console.warn).toHaveBeenCalledWith('update check failed', expect.any(Error));
+  });
+
+  it('should return null if no update is available', async () => {
+    vi.mocked(storage.isTauri).mockReturnValue(true);
+    const { check } = await import('@tauri-apps/plugin-updater');
+    const { getVersion } = await import('@tauri-apps/api/app');
+
+    vi.mocked(check).mockResolvedValue(null);
+    vi.mocked(getVersion).mockResolvedValue('1.0.0');
+
+    const result = await checkForUpdate();
+    expect(result).toBeNull();
+    expect(console.info).toHaveBeenCalledWith("no update: running 1.0.0, that's the latest published release");
+  });
+
+  it('should return an update object if an update is available', async () => {
+    vi.mocked(storage.isTauri).mockReturnValue(true);
+    const { check } = await import('@tauri-apps/plugin-updater');
+
+    const mockUpdate = {
+      version: '1.1.0',
+      currentVersion: '1.0.0',
+      downloadAndInstall: vi.fn().mockResolvedValue(undefined),
+    } as unknown as Update;
+    vi.mocked(check).mockResolvedValue(mockUpdate);
+
+    const result = await checkForUpdate();
+    expect(result).not.toBeNull();
+    if (result !== 'error' && result !== null) {
+      expect(result.version).toBe('1.1.0');
+
+      const { relaunch } = await import('@tauri-apps/plugin-process');
+      await result.install();
+      expect(mockUpdate.downloadAndInstall).toHaveBeenCalled();
+      expect(relaunch).toHaveBeenCalled();
+    }
+  });
+});