diff --git a/.gitignore b/.gitignore
index 797ad06..1c93df5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,5 @@ venv/
 *.csv
 *.json
 !devbox.json
+!example_output.json
+!example_output.csv
diff --git a/README.md b/README.md
index 1425e4d..0186428 100644
--- a/README.md
+++ b/README.md
@@ -13,18 +13,15 @@ Extract two-factor authentication (2FA, TFA) secret keys from export QR codes of
 
 ## Dependencies
 
-The protobuf package of Google for proto3 is required for running this script. protobuf >= 3.14 is recommended.
-
-    pip install protobuf
+    pip install -r requirements.txt
 
 Known to work with
 
-* Python 3.6.12 and protobuf 3.14.0
-* Python 3.8.5 and protobuf 3.14.0
+* Python 3.10.6, protobuf 4.21.5, qrcode 7.3.1, and pillow 9.2
 
 ### Optional
 
-For printing QR codes, the qrcode module is required
+For printing QR codes, the qrcode module is required, otherwise it can be omitted.
 
     pip install qrcode[pil]
 
@@ -33,9 +30,11 @@ For printing QR codes, the qrcode module is required
 The export QR code of "Google Authenticator" contains the URL `otpauth-migration://offline?data=...`.
 The data parameter is a base64 encoded proto3 message (Google Protocol Buffers).
 
-Command for regeneration of Python code from proto3 message definition file (only necessary in case of changes of the proto3 message definition):
+Command for regeneration of Python code from proto3 message definition file (only necessary in case of changes of the proto3 message definition or new protobuf versions):
+
+    protoc --python_out=protobuf_generated_python google_auth.proto
 
-    protoc --python_out=generated_python google_auth.proto
+The generated protobuf Python code was generated by protoc 21.5 (https://github.com/protocolbuffers/protobuf/releases/tag/v21.5).
 
 ## References
 
@@ -63,3 +62,13 @@ Install [devbox](https://github.com/jetpack-io/devbox), which is a wrapper for n
 ```
 devbox shell
 ```
+
+## Unit Tests
+
+There are basic unit tests, see `unittest_extract_otp_secret_keys.py`.
+
+Run unit tests:
+
+```
+python -m unittest
+```
diff --git a/example_output.csv b/example_output.csv
new file mode 100644
index 0000000..7815773
--- /dev/null
+++ b/example_output.csv
@@ -0,0 +1,5 @@
+name,secret,issuer,type,url
+pi@raspberrypi,7KSQL2JTUDIS5EF65KLMRQIIGY,raspberrypi,OTP_TOTP,otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY&issuer=raspberrypi
+pi@raspberrypi,7KSQL2JTUDIS5EF65KLMRQIIGY,,OTP_TOTP,otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY
+pi@raspberrypi,7KSQL2JTUDIS5EF65KLMRQIIGY,,OTP_TOTP,otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY
+pi@raspberrypi,7KSQL2JTUDIS5EF65KLMRQIIGY,raspberrypi,OTP_TOTP,otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY&issuer=raspberrypi
diff --git a/example_output.json b/example_output.json
new file mode 100644
index 0000000..3e85fd0
--- /dev/null
+++ b/example_output.json
@@ -0,0 +1,30 @@
+[
+    {
+        "name": "pi@raspberrypi",
+        "secret": "7KSQL2JTUDIS5EF65KLMRQIIGY",
+        "issuer": "raspberrypi",
+        "type": "OTP_TOTP",
+        "url": "otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY&issuer=raspberrypi"
+    },
+    {
+        "name": "pi@raspberrypi",
+        "secret": "7KSQL2JTUDIS5EF65KLMRQIIGY",
+        "issuer": "",
+        "type": "OTP_TOTP",
+        "url": "otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY"
+    },
+    {
+        "name": "pi@raspberrypi",
+        "secret": "7KSQL2JTUDIS5EF65KLMRQIIGY",
+        "issuer": "",
+        "type": "OTP_TOTP",
+        "url": "otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY"
+    },
+    {
+        "name": "pi@raspberrypi",
+        "secret": "7KSQL2JTUDIS5EF65KLMRQIIGY",
+        "issuer": "raspberrypi",
+        "type": "OTP_TOTP",
+        "url": "otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY&issuer=raspberrypi"
+    }
+]
\ No newline at end of file
diff --git a/extract_otp_secret_keys.py b/extract_otp_secret_keys.py
index 94ad8db..788e91f 100644
--- a/extract_otp_secret_keys.py
+++ b/extract_otp_secret_keys.py
@@ -50,19 +50,7 @@ import json
 from urllib.parse import parse_qs, urlencode, urlparse, quote
 from os import path, mkdir
 from re import sub, compile as rcompile
-import generated_python.google_auth_pb2
-
-arg_parser = argparse.ArgumentParser()
-arg_parser.add_argument('--verbose', '-v', help='verbose output', action='store_true')
-arg_parser.add_argument('--saveqr', '-s', help='save QR code(s) as images to the "qr" subfolder', action='store_true')
-arg_parser.add_argument('--printqr', '-p', help='print QR code(s) as text to the terminal', action='store_true')
-arg_parser.add_argument('--json', '-j', help='export to json file')
-arg_parser.add_argument('--csv', '-c', help='export to csv file')
-arg_parser.add_argument('infile', help='file or - for stdin (default: -) with "otpauth-migration://..." URLs separated by newlines, lines starting with # are ignored')
-args = arg_parser.parse_args()
-
-if args.saveqr or args.printqr: from qrcode import QRCode
-verbose = args.verbose
+import protobuf_generated_python.google_auth_pb2
 
 # https://stackoverflow.com/questions/40226049/find-enums-listed-in-python-descriptor-for-protobuf
 def get_enum_name_by_number(parent, field_name):
@@ -73,6 +61,7 @@ def convert_secret_from_bytes_to_base32_str(bytes):
     return str(base64.b32encode(bytes), 'utf-8').replace('=', '')
 
 def save_qr(data, name):
+    global verbose
     qr = QRCode()
     qr.add_data(data)
     img = qr.make_image(fill_color='black', back_color='white')
@@ -84,66 +73,107 @@ def print_qr(data):
     qr.add_data(data)
     qr.print_ascii()
 
-otps = []
-
-i = j = 0
-for line in (line.strip() for line in fileinput.input(args.infile)):
-    if verbose: print(line)
-    if line.startswith('#') or line == '': continue
-    if not line.startswith('otpauth-migration://'): print('\nWARN: line is not a otpauth-migration:// URL\ninput file: {}\nline "{}"\nProbably a wrong file was given'.format(args.infile, line))
-    parsed_url = urlparse(line)
-    params = parse_qs(parsed_url.query)
-    if not 'data' in params:
-        print('\nERROR: no data query parameter in input URL\ninput file: {}\nline "{}"\nProbably a wrong file was given'.format(args.infile, line))
+def parse_args(sys_args):
+    arg_parser = argparse.ArgumentParser()
+    arg_parser.add_argument('--verbose', '-v', help='verbose output', action='store_true')
+    arg_parser.add_argument('--quiet', '-q', help='no stdout output', action='store_true')
+    arg_parser.add_argument('--saveqr', '-s', help='save QR code(s) as images to the "qr" subfolder', action='store_true')
+    arg_parser.add_argument('--printqr', '-p', help='print QR code(s) as text to the terminal', action='store_true')
+    arg_parser.add_argument('--json', '-j', help='export to json file')
+    arg_parser.add_argument('--csv', '-c', help='export to csv file')
+    arg_parser.add_argument('infile', help='file or - for stdin (default: -) with "otpauth-migration://..." URLs separated by newlines, lines starting with # are ignored')
+    args = arg_parser.parse_args(sys_args)
+    if args.verbose and args.quiet:
+        print("The arguments --verbose and --quite are mutual exclusive.")
         sys.exit(1)
-    data_encoded = params['data'][0]
-    data = base64.b64decode(data_encoded)
-    payload = generated_python.google_auth_pb2.MigrationPayload()
-    payload.ParseFromString(data)
-    i += 1
-    if verbose: print('\n{}. Payload Line'.format(i), payload, sep='\n')
-
-    # pylint: disable=no-member
-    for otp in payload.otp_parameters:
-        j += 1
-        if verbose: print('\n{}. Secret Key'.format(j))
-        else: print()
-        print('Name:   {}'.format(otp.name))
-        secret = convert_secret_from_bytes_to_base32_str(otp.secret)
-        print('Secret: {}'.format(secret))
-        if otp.issuer: print('Issuer: {}'.format(otp.issuer))
-        otp_type = get_enum_name_by_number(otp, 'type')
-        print('Type:   {}'.format(otp_type))
-        url_params = { 'secret': secret }
-        if otp.type == 1: url_params['counter'] = otp.counter
-        if otp.issuer: url_params['issuer'] = otp.issuer
-        otp_url = 'otpauth://{}/{}?'.format('totp' if otp.type == 2 else 'hotp', quote(otp.name)) + urlencode(url_params)
-        if verbose: print(otp_url)
-        if args.printqr:
-            print_qr(otp_url)
-        if args.saveqr:
-            if not(path.exists('qr')): mkdir('qr')
-            pattern = rcompile(r'[\W_]+')
-            file_otp_name = pattern.sub('', otp.name)
-            file_otp_issuer = pattern.sub('', otp.issuer)
-            save_qr(otp_url, 'qr/{}-{}{}.png'.format(j, file_otp_name, '-' + file_otp_issuer if file_otp_issuer else ''))
-
-        otps.append({
-            "name": otp.name,
-            "secret": secret,
-            "issuer": otp.issuer,
-            "type": otp_type,
-            "url": otp_url
-            })
-
-if args.csv and len(otps) > 0:
-    with open(args.csv, "w") as outfile:
-        writer = csv.DictWriter(outfile, otps[0].keys())
-        writer.writeheader()
-        writer.writerows(otps)
-    print("Exported {} otps to csv".format(len(otps)))
-
-if args.json:
-    with open(args.json, "w") as outfile:
-        json.dump(otps, outfile, indent = 4)
-    print("Exported {} otp entries to json".format(len(otps)))
+    return args
+
+def sys_main():
+    main(sys.argv[1:])
+
+def main(sys_args):
+    global verbose, quiet
+    args = parse_args(sys_args)
+    if args.saveqr or args.printqr: from qrcode import QRCode
+    verbose = args.verbose
+    quiet = args.quiet
+
+    otps = extract_otps(args)
+    write_csv(args, otps)
+    write_json(args, otps)
+
+def extract_otps(args):
+    global verbose, quiet
+    quiet = args.quiet
+
+    otps = []
+
+    i = j = 0
+    for line in (line.strip() for line in fileinput.input(args.infile)):
+        if verbose: print(line)
+        if line.startswith('#') or line == '': continue
+        if not line.startswith('otpauth-migration://'): print('\nWARN: line is not a otpauth-migration:// URL\ninput file: {}\nline "{}"\nProbably a wrong file was given'.format(args.infile, line))
+        parsed_url = urlparse(line)
+        params = parse_qs(parsed_url.query)
+        if not 'data' in params:
+            print('\nERROR: no data query parameter in input URL\ninput file: {}\nline "{}"\nProbably a wrong file was given'.format(args.infile, line))
+            sys.exit(1)
+        data_encoded = params['data'][0]
+        data = base64.b64decode(data_encoded)
+        payload = protobuf_generated_python.google_auth_pb2.MigrationPayload()
+        payload.ParseFromString(data)
+        i += 1
+        if verbose: print('\n{}. Payload Line'.format(i), payload, sep='\n')
+
+        # pylint: disable=no-member
+        for otp in payload.otp_parameters:
+            j += 1
+            if verbose: print('\n{}. Secret Key'.format(j))
+            if not quiet: print('Name:   {}'.format(otp.name))
+            secret = convert_secret_from_bytes_to_base32_str(otp.secret)
+            if not quiet: print('Secret: {}'.format(secret))
+            if otp.issuer and not quiet: print('Issuer: {}'.format(otp.issuer))
+            otp_type = get_enum_name_by_number(otp, 'type')
+            if not quiet: print('Type:   {}'.format(otp_type))
+            url_params = { 'secret': secret }
+            if otp.type == 1: url_params['counter'] = otp.counter
+            if otp.issuer: url_params['issuer'] = otp.issuer
+            otp_url = 'otpauth://{}/{}?'.format('totp' if otp.type == 2 else 'hotp', quote(otp.name)) + urlencode(url_params)
+            if verbose: print(otp_url)
+            if args.printqr:
+                print_qr(otp_url)
+            if args.saveqr:
+                if not(path.exists('qr')): mkdir('qr')
+                pattern = rcompile(r'[\W_]+')
+                file_otp_name = pattern.sub('', otp.name)
+                file_otp_issuer = pattern.sub('', otp.issuer)
+                save_qr(otp_url, 'qr/{}-{}{}.png'.format(j, file_otp_name, '-' + file_otp_issuer if file_otp_issuer else ''))
+            if not quiet: print()
+
+            otps.append({
+                "name": otp.name,
+                "secret": secret,
+                "issuer": otp.issuer,
+                "type": otp_type,
+                "url": otp_url
+                })
+    return otps
+
+def write_csv(args, otps):
+    global verbose, quiet
+    if args.csv and len(otps) > 0:
+        with open(args.csv, "w") as outfile:
+            writer = csv.DictWriter(outfile, otps[0].keys())
+            writer.writeheader()
+            writer.writerows(otps)
+        if not quiet: print("Exported {} otps to csv".format(len(otps)))
+
+def write_json(args, otps):
+    global verbose, quiet
+    if args.json:
+        with open(args.json, "w") as outfile:
+            json.dump(otps, outfile, indent = 4)
+        if not quiet: print("Exported {} otp entries to json".format(len(otps)))
+
+if __name__ == '__main__':
+    sys_main()
diff --git a/generated_python/google_auth_pb2.py b/generated_python/google_auth_pb2.py
deleted file mode 100644
index 62ecd04..0000000
--- a/generated_python/google_auth_pb2.py
+++ /dev/null
@@ -1,242 +0,0 @@
-# -*- coding: utf-8 -*-
-# Generated by the protocol buffer compiler.  DO NOT EDIT!
-# source: google_auth.proto
-"""Generated protocol buffer code."""
-from google.protobuf import descriptor as _descriptor
-from google.protobuf import message as _message
-from google.protobuf import reflection as _reflection
-from google.protobuf import symbol_database as _symbol_database
-# @@protoc_insertion_point(imports)
-
-_sym_db = _symbol_database.Default()
-
-
-
-
-DESCRIPTOR = _descriptor.FileDescriptor(
-  name='google_auth.proto',
-  package='',
-  syntax='proto3',
-  serialized_options=None,
-  create_key=_descriptor._internal_create_key,
-  serialized_pb=b'\n\x11google_auth.proto\"\xb7\x03\n\x10MigrationPayload\x12\x37\n\x0eotp_parameters\x18\x01 \x03(\x0b\x32\x1f.MigrationPayload.OtpParameters\x12\x0f\n\x07version\x18\x02 \x01(\x05\x12\x12\n\nbatch_size\x18\x03 \x01(\x05\x12\x13\n\x0b\x62\x61tch_index\x18\x04 \x01(\x05\x12\x10\n\x08\x62\x61tch_id\x18\x05 \x01(\x05\x1a\xb7\x01\n\rOtpParameters\x12\x0e\n\x06secret\x18\x01 \x01(\x0c\x12\x0c\n\x04name\x18\x02 \x01(\t\x12\x0e\n\x06issuer\x18\x03 \x01(\t\x12.\n\talgorithm\x18\x04 \x01(\x0e\x32\x1b.MigrationPayload.Algorithm\x12\x0e\n\x06\x64igits\x18\x05 \x01(\x05\x12\'\n\x04type\x18\x06 \x01(\x0e\x32\x19.MigrationPayload.OtpType\x12\x0f\n\x07\x63ounter\x18\x07 \x01(\x03\",\n\tAlgorithm\x12\x10\n\x0c\x41LGO_INVALID\x10\x00\x12\r\n\tALGO_SHA1\x10\x01\"6\n\x07OtpType\x12\x0f\n\x0bOTP_INVALID\x10\x00\x12\x0c\n\x08OTP_HOTP\x10\x01\x12\x0c\n\x08OTP_TOTP\x10\x02\x62\x06proto3'
-)
-
-
-
-_MIGRATIONPAYLOAD_ALGORITHM = _descriptor.EnumDescriptor(
-  name='Algorithm',
-  full_name='MigrationPayload.Algorithm',
-  filename=None,
-  file=DESCRIPTOR,
-  create_key=_descriptor._internal_create_key,
-  values=[
-    _descriptor.EnumValueDescriptor(
-      name='ALGO_INVALID', index=0, number=0,
-      serialized_options=None,
-      type=None,
-      create_key=_descriptor._internal_create_key),
-    _descriptor.EnumValueDescriptor(
-      name='ALGO_SHA1', index=1, number=1,
-      serialized_options=None,
-      type=None,
-      create_key=_descriptor._internal_create_key),
-  ],
-  containing_type=None,
-  serialized_options=None,
-  serialized_start=361,
-  serialized_end=405,
-)
-_sym_db.RegisterEnumDescriptor(_MIGRATIONPAYLOAD_ALGORITHM)
-
-_MIGRATIONPAYLOAD_OTPTYPE = _descriptor.EnumDescriptor(
-  name='OtpType',
-  full_name='MigrationPayload.OtpType',
-  filename=None,
-  file=DESCRIPTOR,
-  create_key=_descriptor._internal_create_key,
-  values=[
-    _descriptor.EnumValueDescriptor(
-      name='OTP_INVALID', index=0, number=0,
-      serialized_options=None,
-      type=None,
-      create_key=_descriptor._internal_create_key),
-    _descriptor.EnumValueDescriptor(
-      name='OTP_HOTP', index=1, number=1,
-      serialized_options=None,
-      type=None,
-      create_key=_descriptor._internal_create_key),
-    _descriptor.EnumValueDescriptor(
-      name='OTP_TOTP', index=2, number=2,
-      serialized_options=None,
-      type=None,
-      create_key=_descriptor._internal_create_key),
-  ],
-  containing_type=None,
-  serialized_options=None,
-  serialized_start=407,
-  serialized_end=461,
-)
-_sym_db.RegisterEnumDescriptor(_MIGRATIONPAYLOAD_OTPTYPE)
-
-
-_MIGRATIONPAYLOAD_OTPPARAMETERS = _descriptor.Descriptor(
-  name='OtpParameters',
-  full_name='MigrationPayload.OtpParameters',
-  filename=None,
-  file=DESCRIPTOR,
-  containing_type=None,
-  create_key=_descriptor._internal_create_key,
-  fields=[
-    _descriptor.FieldDescriptor(
-      name='secret', full_name='MigrationPayload.OtpParameters.secret', index=0,
-      number=1, type=12, cpp_type=9, label=1,
-      has_default_value=False, default_value=b"",
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-    _descriptor.FieldDescriptor(
-      name='name', full_name='MigrationPayload.OtpParameters.name', index=1,
-      number=2, type=9, cpp_type=9, label=1,
-      has_default_value=False, default_value=b"".decode('utf-8'),
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-    _descriptor.FieldDescriptor(
-      name='issuer', full_name='MigrationPayload.OtpParameters.issuer', index=2,
-      number=3, type=9, cpp_type=9, label=1,
-      has_default_value=False, default_value=b"".decode('utf-8'),
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-    _descriptor.FieldDescriptor(
-      name='algorithm', full_name='MigrationPayload.OtpParameters.algorithm', index=3,
-      number=4, type=14, cpp_type=8, label=1,
-      has_default_value=False, default_value=0,
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-    _descriptor.FieldDescriptor(
-      name='digits', full_name='MigrationPayload.OtpParameters.digits', index=4,
-      number=5, type=5, cpp_type=1, label=1,
-      has_default_value=False, default_value=0,
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-    _descriptor.FieldDescriptor(
-      name='type', full_name='MigrationPayload.OtpParameters.type', index=5,
-      number=6, type=14, cpp_type=8, label=1,
-      has_default_value=False, default_value=0,
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-    _descriptor.FieldDescriptor(
-      name='counter', full_name='MigrationPayload.OtpParameters.counter', index=6,
-      number=7, type=3, cpp_type=2, label=1,
-      has_default_value=False, default_value=0,
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-  ],
-  extensions=[
-  ],
-  nested_types=[],
-  enum_types=[
-  ],
-  serialized_options=None,
-  is_extendable=False,
-  syntax='proto3',
-  extension_ranges=[],
-  oneofs=[
-  ],
-  serialized_start=176,
-  serialized_end=359,
-)
-
-_MIGRATIONPAYLOAD = _descriptor.Descriptor(
-  name='MigrationPayload',
-  full_name='MigrationPayload',
-  filename=None,
-  file=DESCRIPTOR,
-  containing_type=None,
-  create_key=_descriptor._internal_create_key,
-  fields=[
-    _descriptor.FieldDescriptor(
-      name='otp_parameters', full_name='MigrationPayload.otp_parameters', index=0,
-      number=1, type=11, cpp_type=10, label=3,
-      has_default_value=False, default_value=[],
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-    _descriptor.FieldDescriptor(
-      name='version', full_name='MigrationPayload.version', index=1,
-      number=2, type=5, cpp_type=1, label=1,
-      has_default_value=False, default_value=0,
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-    _descriptor.FieldDescriptor(
-      name='batch_size', full_name='MigrationPayload.batch_size', index=2,
-      number=3, type=5, cpp_type=1, label=1,
-      has_default_value=False, default_value=0,
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-    _descriptor.FieldDescriptor(
-      name='batch_index', full_name='MigrationPayload.batch_index', index=3,
-      number=4, type=5, cpp_type=1, label=1,
-      has_default_value=False, default_value=0,
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-    _descriptor.FieldDescriptor(
-      name='batch_id', full_name='MigrationPayload.batch_id', index=4,
-      number=5, type=5, cpp_type=1, label=1,
-      has_default_value=False, default_value=0,
-      message_type=None, enum_type=None, containing_type=None,
-      is_extension=False, extension_scope=None,
-      serialized_options=None, file=DESCRIPTOR,  create_key=_descriptor._internal_create_key),
-  ],
-  extensions=[
-  ],
-  nested_types=[_MIGRATIONPAYLOAD_OTPPARAMETERS, ],
-  enum_types=[
-    _MIGRATIONPAYLOAD_ALGORITHM,
-    _MIGRATIONPAYLOAD_OTPTYPE,
-  ],
-  serialized_options=None,
-  is_extendable=False,
-  syntax='proto3',
-  extension_ranges=[],
-  oneofs=[
-  ],
-  serialized_start=22,
-  serialized_end=461,
-)
-
-_MIGRATIONPAYLOAD_OTPPARAMETERS.fields_by_name['algorithm'].enum_type = _MIGRATIONPAYLOAD_ALGORITHM
-_MIGRATIONPAYLOAD_OTPPARAMETERS.fields_by_name['type'].enum_type = _MIGRATIONPAYLOAD_OTPTYPE
-_MIGRATIONPAYLOAD_OTPPARAMETERS.containing_type = _MIGRATIONPAYLOAD
-_MIGRATIONPAYLOAD.fields_by_name['otp_parameters'].message_type = _MIGRATIONPAYLOAD_OTPPARAMETERS
-_MIGRATIONPAYLOAD_ALGORITHM.containing_type = _MIGRATIONPAYLOAD
-_MIGRATIONPAYLOAD_OTPTYPE.containing_type = _MIGRATIONPAYLOAD
-DESCRIPTOR.message_types_by_name['MigrationPayload'] = _MIGRATIONPAYLOAD
-_sym_db.RegisterFileDescriptor(DESCRIPTOR)
-
-MigrationPayload = _reflection.GeneratedProtocolMessageType('MigrationPayload', (_message.Message,), {
-
-  'OtpParameters' : _reflection.GeneratedProtocolMessageType('OtpParameters', (_message.Message,), {
-    'DESCRIPTOR' : _MIGRATIONPAYLOAD_OTPPARAMETERS,
-    '__module__' : 'google_auth_pb2'
-    # @@protoc_insertion_point(class_scope:MigrationPayload.OtpParameters)
-    })
-  ,
-  'DESCRIPTOR' : _MIGRATIONPAYLOAD,
-  '__module__' : 'google_auth_pb2'
-  # @@protoc_insertion_point(class_scope:MigrationPayload)
-  })
-_sym_db.RegisterMessage(MigrationPayload)
-_sym_db.RegisterMessage(MigrationPayload.OtpParameters)
-
-
-# @@protoc_insertion_point(module_scope)
diff --git a/protobuf_generated_python/google_auth_pb2.py b/protobuf_generated_python/google_auth_pb2.py
new file mode 100644
index 0000000..7099ee4
--- /dev/null
+++ b/protobuf_generated_python/google_auth_pb2.py
@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google_auth.proto
+"""Generated protocol buffer code."""
+from google.protobuf.internal import builder as _builder
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import descriptor_pool as _descriptor_pool
+from google.protobuf import symbol_database as _symbol_database
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+
+
+DESCRIPTOR = _descriptor_pool.Default().AddSerializedFile(b'\n\x11google_auth.proto\"\xb7\x03\n\x10MigrationPayload\x12\x37\n\x0eotp_parameters\x18\x01 \x03(\x0b\x32\x1f.MigrationPayload.OtpParameters\x12\x0f\n\x07version\x18\x02 \x01(\x05\x12\x12\n\nbatch_size\x18\x03 \x01(\x05\x12\x13\n\x0b\x62\x61tch_index\x18\x04 \x01(\x05\x12\x10\n\x08\x62\x61tch_id\x18\x05 \x01(\x05\x1a\xb7\x01\n\rOtpParameters\x12\x0e\n\x06secret\x18\x01 \x01(\x0c\x12\x0c\n\x04name\x18\x02 \x01(\t\x12\x0e\n\x06issuer\x18\x03 \x01(\t\x12.\n\talgorithm\x18\x04 \x01(\x0e\x32\x1b.MigrationPayload.Algorithm\x12\x0e\n\x06\x64igits\x18\x05 \x01(\x05\x12\'\n\x04type\x18\x06 \x01(\x0e\x32\x19.MigrationPayload.OtpType\x12\x0f\n\x07\x63ounter\x18\x07 \x01(\x03\",\n\tAlgorithm\x12\x10\n\x0c\x41LGO_INVALID\x10\x00\x12\r\n\tALGO_SHA1\x10\x01\"6\n\x07OtpType\x12\x0f\n\x0bOTP_INVALID\x10\x00\x12\x0c\n\x08OTP_HOTP\x10\x01\x12\x0c\n\x08OTP_TOTP\x10\x02\x62\x06proto3')
+
+_builder.BuildMessageAndEnumDescriptors(DESCRIPTOR, globals())
+_builder.BuildTopDescriptorsAndMessages(DESCRIPTOR, 'google_auth_pb2', globals())
+if _descriptor._USE_C_DESCRIPTORS == False:
+
+  DESCRIPTOR._options = None
+  _MIGRATIONPAYLOAD._serialized_start=22
+  _MIGRATIONPAYLOAD._serialized_end=461
+  _MIGRATIONPAYLOAD_OTPPARAMETERS._serialized_start=176
+  _MIGRATIONPAYLOAD_OTPPARAMETERS._serialized_end=359
+  _MIGRATIONPAYLOAD_ALGORITHM._serialized_start=361
+  _MIGRATIONPAYLOAD_ALGORITHM._serialized_end=405
+  _MIGRATIONPAYLOAD_OTPTYPE._serialized_start=407
+  _MIGRATIONPAYLOAD_OTPTYPE._serialized_end=461
+# @@protoc_insertion_point(module_scope)
diff --git a/unittest_extract_otp_secret_keys.py b/unittest_extract_otp_secret_keys.py
new file mode 100644
index 0000000..e101118
--- /dev/null
+++ b/unittest_extract_otp_secret_keys.py
@@ -0,0 +1,75 @@
+# Unit test for extract_otp_secret_keys.py
+
+# Run tests:
+# python -m unittest
+
+# Author: Scito (https://scito.ch)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import unittest
+import csv
+import json
+import os
+
+import extract_otp_secret_keys
+
+class TestExtract(unittest.TestCase):
+
+    def test_extract_csv(self):
+        extract_otp_secret_keys.main(['-q', '-c', 'test_example_output.csv', 'example_export.txt'])
+
+        expected_csv = read_csv('example_output.csv')
+        actual_csv = read_csv('test_example_output.csv')
+
+        self.assertEqual(actual_csv, expected_csv)
+
+    def test_extract_json(self):
+        extract_otp_secret_keys.main(['-q', '-j', 'test_example_output.json', 'example_export.txt'])
+
+        expected_json = read_json('example_output.json')
+        actual_json = read_json('test_example_output.json')
+
+        self.assertEqual(actual_json, expected_json)
+
+    def setUp(self):
+        self.cleanup()
+
+    def tearDown(self):
+        self.cleanup()
+
+    def cleanup(self):
+        remove_file('test_example_output.csv')
+        remove_file('test_example_output.json')
+
+def remove_file(filename):
+    if os.path.exists(filename): os.remove(filename)
+
+def read_csv(filename):
+    """Returns a list of lines."""
+    with open(filename, "r") as infile:
+        lines = []
+        reader = csv.reader(infile)
+        for line in reader:
+            lines.append(line)
+        return lines
+
+def read_json(filename):
+    """Returns a list or a dictionary."""
+    with open(filename, "r") as infile:
+        return json.load(infile)
+
+
+if __name__ == '__main__':
+    unittest.main()