diff --git a/.gitignore b/.gitignore
index 9b976cc..c246afc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,3 +17,7 @@ __pycache__/
 
 # vCards
 vcards
+
+#
+anmeldung.sqbpro
+CHAT_SUMMARY.md
diff --git a/app.py b/app.py
index e3d8527..5bd526c 100644
--- a/app.py
+++ b/app.py
@@ -2,8 +2,7 @@ from flask import Flask, render_template, request, redirect, url_for
 from flask_sqlalchemy import SQLAlchemy
 import os
 import re
-import pathlib
-import unicodedata
+from utils import generate_vcard
 
 BASE_DIR = os.path.dirname(os.path.abspath(__file__))
 DB_PATH = os.path.join(BASE_DIR, 'anmeldung.db')
@@ -98,42 +97,8 @@ def index():
 
         # vCard 4.0 erzeugen und speichern
         try:
-            vcards_dir = os.path.join(BASE_DIR, 'vcards')
-            os.makedirs(vcards_dir, exist_ok=True)
-
-            # sanitize filename: remove diacritics and unsafe chars
-            def slug(s):
-                s = unicodedata.normalize('NFKD', s)
-                s = ''.join(c for c in s if not unicodedata.combining(c))
-                s = ''.join(c for c in s if c.isalnum() or c in (' ', '_', '-'))
-                return s.replace(' ', '_')
-
-            filename = f"{slug(adresse.nachname)}_{slug(adresse.vorname)}_{adresse.id}.vcf"
-            filepath = os.path.join(vcards_dir, filename)
-
-            # build vCard 4.0 content
-            lines = [
-                'BEGIN:VCARD',
-                'VERSION:4.0',
-                f'N:{adresse.nachname};{adresse.vorname};;;',
-                f'FN:{adresse.vorname} {adresse.nachname}',
-            ]
-            # ADR: PO Box;Extended;Street;Locality;Region;PostalCode;Country
-            street = adresse.strasse or ''
-            if adresse.hausnummer:
-                street = f"{street} {adresse.hausnummer}".strip()
-            adr = f'ADR:;;{street};{adresse.ort};;{adresse.plz};{adresse.land}'
-            lines.append(adr)
-            if adresse.email:
-                lines.append(f'EMAIL;TYPE=internet:{adresse.email}')
-            phone = ''
-            if adresse.telefon_vorwahl or adresse.telefon_nummer:
-                phone = f"+{adresse.telefon_vorwahl}{adresse.telefon_nummer}".replace('++', '+')
-                lines.append(f'TEL;TYPE=voice:{phone}')
-            lines.append('END:VCARD')
-
-            with open(filepath, 'w', encoding='utf-8') as f:
-                f.write('\n'.join(lines))
+            # generate vcard using helper
+            generate_vcard(adresse, BASE_DIR)
         except Exception:
             # nicht kritisch: bei Fehlern nicht die ganze Anfrage abbrechen
             pass
diff --git a/requirements-dev.txt b/requirements-dev.txt
new file mode 100644
index 0000000..e079f8a
--- /dev/null
+++ b/requirements-dev.txt
@@ -0,0 +1 @@
+pytest
diff --git a/tests/test_utils_vcard.py b/tests/test_utils_vcard.py
new file mode 100644
index 0000000..4bbdf3b
--- /dev/null
+++ b/tests/test_utils_vcard.py
@@ -0,0 +1,29 @@
+from types import SimpleNamespace
+from pathlib import Path
+
+from utils import generate_vcard
+
+
+def test_generate_vcard_writes_file(tmp_path):
+    addr = SimpleNamespace(
+        vorname='Anna',
+        nachname='Muster',
+        strasse='Beispielweg',
+        hausnummer='5a',
+        plz='54321',
+        ort='Beispielstadt',
+        land='Deutschland',
+        email='anna@example.com',
+        telefon_vorwahl='49',
+        telefon_nummer='7654321',
+        id=42,
+    )
+
+    path = generate_vcard(addr, str(tmp_path))
+    assert Path(path).exists()
+
+    content = Path(path).read_text(encoding='utf-8')
+    assert 'BEGIN:VCARD' in content
+    assert 'FN:Anna Muster' in content
+    assert 'EMAIL;TYPE=internet:anna@example.com' in content
+    assert 'TEL;TYPE=voice:+497654321' in content
diff --git a/tests/test_vcard_export.py b/tests/test_vcard_export.py
new file mode 100644
index 0000000..94fdc1b
--- /dev/null
+++ b/tests/test_vcard_export.py
@@ -0,0 +1,62 @@
+import pytest
+from pathlib import Path
+
+from app import app, db, Frage
+
+
+@pytest.fixture
+def client(tmp_path, monkeypatch):
+    # Use a temporary directory for vcards and a temporary sqlite db
+    # temp DB file
+    db_file = tmp_path / "test.db"
+
+    # Configure app for testing
+    app.config['TESTING'] = True
+    app.config['SQLALCHEMY_DATABASE_URI'] = f'sqlite:///{db_file}'
+
+    # Use temp vcards dir by setting app.BASE_DIR
+    app.BASE_DIR = str(tmp_path)
+
+    # ensure clean DB and create tables
+    with app.app_context():
+        db.drop_all()
+        db.create_all()
+        # create a sample question so POST processing loops over it
+        q = Frage(text='Testfrage?')
+        db.session.add(q)
+        db.session.commit()
+
+    with app.test_client() as test_client:
+        yield test_client
+
+
+def test_vcard_created_after_submit(client, tmp_path):
+    data = {
+        'vorname': 'Max',
+        'nachname': 'Mustermann',
+        'strasse': 'Musterstraße',
+        'hausnummer': '1',
+        'plz': '12345',
+        'ort': 'Musterstadt',
+        'land': 'Deutschland',
+        'telefon_vorwahl': '49',
+        'telefon_nummer': '1234567',
+        'email': 'max@example.com',
+        'frage_1': 'Antwort'
+    }
+
+    # Submit the form
+    res = client.post('/', data=data, follow_redirects=True)
+    assert res.status_code == 200
+
+    # find vcards dir under tmp_path (app.BASE_DIR)
+    vcards_dir = Path(app.BASE_DIR) / 'vcards'
+    files = list(vcards_dir.glob('*.vcf'))
+    assert len(files) == 1
+
+    content = files[0].read_text(encoding='utf-8')
+    assert 'BEGIN:VCARD' in content
+    assert 'VERSION:4.0' in content
+    assert 'FN:Max Mustermann' in content
+    assert 'EMAIL;TYPE=internet:max@example.com' in content
+    assert 'ADR:' in content
diff --git a/utils.py b/utils.py
new file mode 100644
index 0000000..ba9a740
--- /dev/null
+++ b/utils.py
@@ -0,0 +1,57 @@
+import os
+import unicodedata
+
+
+def _slug(s: str) -> str:
+    if not s:
+        return ''
+    s = unicodedata.normalize('NFKD', s)
+    s = ''.join(c for c in s if not unicodedata.combining(c))
+    s = ''.join(c for c in s if c.isalnum() or c in (' ', '_', '-'))
+    return s.replace(' ', '_')
+
+
+def generate_vcard(adresse, base_dir: str):
+    """Generate a vCard 4.0 file for the given adresse object.
+
+    adresse: object with attributes vorname, nachname, strasse, hausnummer,
+             plz, ort, land, email, telefon_vorwahl, telefon_nummer, id
+    base_dir: directory where 'vcards/' will be created
+
+    Returns the path to the written vcard file.
+    """
+    vcards_dir = os.path.join(base_dir, 'vcards')
+    os.makedirs(vcards_dir, exist_ok=True)
+
+    filename = f"{_slug(adresse.nachname)}_{_slug(adresse.vorname)}_{adresse.id}.vcf"
+    filepath = os.path.join(vcards_dir, filename)
+
+    # build vCard 4.0 content
+    lines = [
+        'BEGIN:VCARD',
+        'VERSION:4.0',
+        f'N:{adresse.nachname};{adresse.vorname};;;',
+        f'FN:{adresse.vorname} {adresse.nachname}',
+    ]
+
+    street = getattr(adresse, 'strasse', '') or ''
+    hausnummer = getattr(adresse, 'hausnummer', '') or ''
+    if hausnummer:
+        street = f"{street} {hausnummer}".strip()
+
+    adr = f'ADR:;;{street};{getattr(adresse, "ort", "")};;{getattr(adresse, "plz", "")};{getattr(adresse, "land", "")}'
+    lines.append(adr)
+
+    if getattr(adresse, 'email', None):
+        lines.append(f'EMAIL;TYPE=internet:{adresse.email}')
+
+    if getattr(adresse, 'telefon_vorwahl', None) or getattr(adresse, 'telefon_nummer', None):
+        tel = f"+{getattr(adresse, 'telefon_vorwahl', '')}{getattr(adresse, 'telefon_nummer', '')}".replace('++', '+')
+        lines.append(f'TEL;TYPE=voice:{tel}')
+
+    lines.append('END:VCARD')
+
+    with open(filepath, 'w', encoding='utf-8') as f:
+        f.write('\n'.join(lines))
+
+    return filepath