fix(cardav): improve router security and test coverage

- Remove error message leakage (return generic 'Interner Fehler')
- Remove unused imports (str, collectErrors, MAX_TITLE, MAX_URL)
- Add _resetTestDatabase() for proper test cleanup
- Add test for populated accounts case with shape validation
- Import 'after' from node:test for proper teardown

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

server/db.js

@@ -1354,14 +1354,27 @@ function transaction(fn) {
   return get().transaction(fn)();
 }
 
+let _originalDb = null;
+
 /**
  * ONLY FOR TESTING: Override the internal db instance
  * @param {import('better-sqlite3').Database} testDb
  */
 function _setTestDatabase(testDb) {
+  if (!_originalDb) _originalDb = db;
   db = testDb;
 }
 
+/**
+ * ONLY FOR TESTING: Restore the original db instance
+ */
+function _resetTestDatabase() {
+  if (_originalDb) {
+    db = _originalDb;
+    _originalDb = null;
+  }
+}
+
 init();   // auto-initialise when module is first imported
 
-export { init, get, transaction, currentVersion, getPath, backupToFile, restoreFromFile, MIGRATIONS, _setTestDatabase };
+export { init, get, transaction, currentVersion, getPath, backupToFile, restoreFromFile, MIGRATIONS, _setTestDatabase, _resetTestDatabase };

server/routes/cardav.js

@@ -6,13 +6,9 @@
 
 import { createLogger } from '../logger.js';
 import express from 'express';
-import * as db from '../db.js';
 import * as CardDAVSync from '../services/cardav-sync.js';
-import { str, collectErrors, MAX_TITLE } from '../middleware/validate.js';
 
 const log = createLogger('CardDAV');
-const MAX_URL = 500;
-
 const router = express.Router();
 
 /**
@@ -26,7 +22,7 @@ router.get('/accounts', async (req, res) => {
     res.json({ data: accounts });
   } catch (err) {
     log.error('Error fetching accounts:', err);
-    res.status(500).json({ error: err.message || 'Interner Fehler', code: 500 });
+    res.status(500).json({ error: 'Interner Fehler', code: 500 });
   }
 });
 

test-carddav.js

@@ -3,7 +3,7 @@
  * Purpose: Verify Migration 30 - CardDAV multi-account contacts sync tables
  */
 
-import { describe, it, before } from 'node:test';
+import { describe, it, before, after } from 'node:test';
 import assert from 'node:assert/strict';
 import Database from 'better-sqlite3';
 import { MIGRATIONS } from './server/db.js';
@@ -1515,6 +1515,12 @@ describe('CardDAV API Routes', () => {
     dbModule._setTestDatabase(apiTestDb);
   });
 
+  after(async () => {
+    // Restore original database
+    const dbModule = await import('./server/db.js');
+    dbModule._resetTestDatabase();
+  });
+
   describe('Account Management', () => {
     it('GET /accounts - should return empty array when no accounts', async () => {
       const cardavRouter = await import('./server/routes/cardav.js');
@@ -1537,5 +1543,38 @@ describe('CardDAV API Routes', () => {
       assert.ok(Array.isArray(res.data.data));
       assert.strictEqual(res.data.data.length, 0);
     });
+
+    it('GET /accounts - should return accounts with correct shape', async () => {
+      // Insert test account
+      apiTestDb.prepare(`
+        INSERT INTO carddav_accounts (name, carddav_url, username, password, created_at)
+        VALUES (?, ?, ?, ?, ?)
+      `).run('Test iCloud', 'https://contacts.icloud.com', 'test@icloud.com', 'secret', '2026-05-01T10:00:00Z');
+
+      const cardavRouter = await import('./server/routes/cardav.js');
+      const req = { params: {}, query: {}, body: {} };
+      const res = {
+        statusCode: 200,
+        status(code) { this.statusCode = code; return this; },
+        json(data) { this.data = data; return this; },
+      };
+
+      const getHandler = cardavRouter.default.stack.find(
+        layer => layer.route?.path === '/accounts' && layer.route.methods.get
+      )?.route?.stack[0]?.handle;
+
+      await getHandler(req, res);
+
+      assert.strictEqual(res.statusCode, 200);
+      assert.ok(Array.isArray(res.data.data));
+      assert.strictEqual(res.data.data.length, 1);
+
+      const account = res.data.data[0];
+      assert.strictEqual(account.name, 'Test iCloud');
+      assert.strictEqual(account.cardavUrl, 'https://contacts.icloud.com');
+      assert.strictEqual(account.username, 'test@icloud.com');
+      assert.strictEqual(account.createdAt, '2026-05-01T10:00:00Z');
+      assert.ok(!account.password, 'Password should not be exposed');
+    });
   });
 });