django/tests/auth_tests/test_hashers.py

599 lines
26 KiB
Python

from unittest import mock, skipUnless
from django.conf.global_settings import PASSWORD_HASHERS
from django.contrib.auth.hashers import (
UNUSABLE_PASSWORD_PREFIX, UNUSABLE_PASSWORD_SUFFIX_LENGTH,
BasePasswordHasher, PBKDF2PasswordHasher, PBKDF2SHA1PasswordHasher,
check_password, get_hasher, identify_hasher, is_password_usable,
make_password,
)
from django.test import SimpleTestCase
from django.test.utils import override_settings
try:
import crypt
except ImportError:
crypt = None
else:
# On some platforms (e.g. OpenBSD), crypt.crypt() always return None.
if crypt.crypt('') is None:
crypt = None
try:
import bcrypt
except ImportError:
bcrypt = None
try:
import argon2
except ImportError:
argon2 = None
class PBKDF2SingleIterationHasher(PBKDF2PasswordHasher):
iterations = 1
@override_settings(PASSWORD_HASHERS=PASSWORD_HASHERS)
class TestUtilsHashPass(SimpleTestCase):
def test_simple(self):
encoded = make_password('lètmein')
self.assertTrue(encoded.startswith('pbkdf2_sha256$'))
self.assertTrue(is_password_usable(encoded))
self.assertTrue(check_password('lètmein', encoded))
self.assertFalse(check_password('lètmeinz', encoded))
# Blank passwords
blank_encoded = make_password('')
self.assertTrue(blank_encoded.startswith('pbkdf2_sha256$'))
self.assertTrue(is_password_usable(blank_encoded))
self.assertTrue(check_password('', blank_encoded))
self.assertFalse(check_password(' ', blank_encoded))
def test_bytes(self):
encoded = make_password(b'bytes_password')
self.assertTrue(encoded.startswith('pbkdf2_sha256$'))
self.assertIs(is_password_usable(encoded), True)
self.assertIs(check_password(b'bytes_password', encoded), True)
def test_invalid_password(self):
msg = 'Password must be a string or bytes, got int.'
with self.assertRaisesMessage(TypeError, msg):
make_password(1)
def test_pbkdf2(self):
encoded = make_password('lètmein', 'seasalt', 'pbkdf2_sha256')
self.assertEqual(encoded, 'pbkdf2_sha256$260000$seasalt$YlZ2Vggtqdc61YjArZuoApoBh9JNGYoDRBUGu6tcJQo=')
self.assertTrue(is_password_usable(encoded))
self.assertTrue(check_password('lètmein', encoded))
self.assertFalse(check_password('lètmeinz', encoded))
self.assertEqual(identify_hasher(encoded).algorithm, "pbkdf2_sha256")
# Blank passwords
blank_encoded = make_password('', 'seasalt', 'pbkdf2_sha256')
self.assertTrue(blank_encoded.startswith('pbkdf2_sha256$'))
self.assertTrue(is_password_usable(blank_encoded))
self.assertTrue(check_password('', blank_encoded))
self.assertFalse(check_password(' ', blank_encoded))
@override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.SHA1PasswordHasher'])
def test_sha1(self):
encoded = make_password('lètmein', 'seasalt', 'sha1')
self.assertEqual(encoded, 'sha1$seasalt$cff36ea83f5706ce9aa7454e63e431fc726b2dc8')
self.assertTrue(is_password_usable(encoded))
self.assertTrue(check_password('lètmein', encoded))
self.assertFalse(check_password('lètmeinz', encoded))
self.assertEqual(identify_hasher(encoded).algorithm, "sha1")
# Blank passwords
blank_encoded = make_password('', 'seasalt', 'sha1')
self.assertTrue(blank_encoded.startswith('sha1$'))
self.assertTrue(is_password_usable(blank_encoded))
self.assertTrue(check_password('', blank_encoded))
self.assertFalse(check_password(' ', blank_encoded))
@override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.MD5PasswordHasher'])
def test_md5(self):
encoded = make_password('lètmein', 'seasalt', 'md5')
self.assertEqual(encoded, 'md5$seasalt$3f86d0d3d465b7b458c231bf3555c0e3')
self.assertTrue(is_password_usable(encoded))
self.assertTrue(check_password('lètmein', encoded))
self.assertFalse(check_password('lètmeinz', encoded))
self.assertEqual(identify_hasher(encoded).algorithm, "md5")
# Blank passwords
blank_encoded = make_password('', 'seasalt', 'md5')
self.assertTrue(blank_encoded.startswith('md5$'))
self.assertTrue(is_password_usable(blank_encoded))
self.assertTrue(check_password('', blank_encoded))
self.assertFalse(check_password(' ', blank_encoded))
@override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.UnsaltedMD5PasswordHasher'])
def test_unsalted_md5(self):
encoded = make_password('lètmein', '', 'unsalted_md5')
self.assertEqual(encoded, '88a434c88cca4e900f7874cd98123f43')
self.assertTrue(is_password_usable(encoded))
self.assertTrue(check_password('lètmein', encoded))
self.assertFalse(check_password('lètmeinz', encoded))
self.assertEqual(identify_hasher(encoded).algorithm, "unsalted_md5")
# Alternate unsalted syntax
alt_encoded = "md5$$%s" % encoded
self.assertTrue(is_password_usable(alt_encoded))
self.assertTrue(check_password('lètmein', alt_encoded))
self.assertFalse(check_password('lètmeinz', alt_encoded))
# Blank passwords
blank_encoded = make_password('', '', 'unsalted_md5')
self.assertTrue(is_password_usable(blank_encoded))
self.assertTrue(check_password('', blank_encoded))
self.assertFalse(check_password(' ', blank_encoded))
@override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.UnsaltedSHA1PasswordHasher'])
def test_unsalted_sha1(self):
encoded = make_password('lètmein', '', 'unsalted_sha1')
self.assertEqual(encoded, 'sha1$$6d138ca3ae545631b3abd71a4f076ce759c5700b')
self.assertTrue(is_password_usable(encoded))
self.assertTrue(check_password('lètmein', encoded))
self.assertFalse(check_password('lètmeinz', encoded))
self.assertEqual(identify_hasher(encoded).algorithm, "unsalted_sha1")
# Raw SHA1 isn't acceptable
alt_encoded = encoded[6:]
self.assertFalse(check_password('lètmein', alt_encoded))
# Blank passwords
blank_encoded = make_password('', '', 'unsalted_sha1')
self.assertTrue(blank_encoded.startswith('sha1$'))
self.assertTrue(is_password_usable(blank_encoded))
self.assertTrue(check_password('', blank_encoded))
self.assertFalse(check_password(' ', blank_encoded))
@skipUnless(crypt, "no crypt module to generate password.")
@override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.CryptPasswordHasher'])
def test_crypt(self):
encoded = make_password('lètmei', 'ab', 'crypt')
self.assertEqual(encoded, 'crypt$$ab1Hv2Lg7ltQo')
self.assertTrue(is_password_usable(encoded))
self.assertTrue(check_password('lètmei', encoded))
self.assertFalse(check_password('lètmeiz', encoded))
self.assertEqual(identify_hasher(encoded).algorithm, "crypt")
# Blank passwords
blank_encoded = make_password('', 'ab', 'crypt')
self.assertTrue(blank_encoded.startswith('crypt$'))
self.assertTrue(is_password_usable(blank_encoded))
self.assertTrue(check_password('', blank_encoded))
self.assertFalse(check_password(' ', blank_encoded))
@skipUnless(bcrypt, "bcrypt not installed")
def test_bcrypt_sha256(self):
encoded = make_password('lètmein', hasher='bcrypt_sha256')
self.assertTrue(is_password_usable(encoded))
self.assertTrue(encoded.startswith('bcrypt_sha256$'))
self.assertTrue(check_password('lètmein', encoded))
self.assertFalse(check_password('lètmeinz', encoded))
self.assertEqual(identify_hasher(encoded).algorithm, "bcrypt_sha256")
# password truncation no longer works
password = (
'VSK0UYV6FFQVZ0KG88DYN9WADAADZO1CTSIVDJUNZSUML6IBX7LN7ZS3R5'
'JGB3RGZ7VI7G7DJQ9NI8BQFSRPTG6UWTTVESA5ZPUN'
)
encoded = make_password(password, hasher='bcrypt_sha256')
self.assertTrue(check_password(password, encoded))
self.assertFalse(check_password(password[:72], encoded))
# Blank passwords
blank_encoded = make_password('', hasher='bcrypt_sha256')
self.assertTrue(blank_encoded.startswith('bcrypt_sha256$'))
self.assertTrue(is_password_usable(blank_encoded))
self.assertTrue(check_password('', blank_encoded))
self.assertFalse(check_password(' ', blank_encoded))
@skipUnless(bcrypt, "bcrypt not installed")
@override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.BCryptPasswordHasher'])
def test_bcrypt(self):
encoded = make_password('lètmein', hasher='bcrypt')
self.assertTrue(is_password_usable(encoded))
self.assertTrue(encoded.startswith('bcrypt$'))
self.assertTrue(check_password('lètmein', encoded))
self.assertFalse(check_password('lètmeinz', encoded))
self.assertEqual(identify_hasher(encoded).algorithm, "bcrypt")
# Blank passwords
blank_encoded = make_password('', hasher='bcrypt')
self.assertTrue(blank_encoded.startswith('bcrypt$'))
self.assertTrue(is_password_usable(blank_encoded))
self.assertTrue(check_password('', blank_encoded))
self.assertFalse(check_password(' ', blank_encoded))
@skipUnless(bcrypt, "bcrypt not installed")
@override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.BCryptPasswordHasher'])
def test_bcrypt_upgrade(self):
hasher = get_hasher('bcrypt')
self.assertEqual('bcrypt', hasher.algorithm)
self.assertNotEqual(hasher.rounds, 4)
old_rounds = hasher.rounds
try:
# Generate a password with 4 rounds.
hasher.rounds = 4
encoded = make_password('letmein', hasher='bcrypt')
rounds = hasher.safe_summary(encoded)['work factor']
self.assertEqual(rounds, 4)
state = {'upgraded': False}
def setter(password):
state['upgraded'] = True
# No upgrade is triggered.
self.assertTrue(check_password('letmein', encoded, setter, 'bcrypt'))
self.assertFalse(state['upgraded'])
# Revert to the old rounds count and ...
hasher.rounds = old_rounds
# ... check if the password would get updated to the new count.
self.assertTrue(check_password('letmein', encoded, setter, 'bcrypt'))
self.assertTrue(state['upgraded'])
finally:
hasher.rounds = old_rounds
@skipUnless(bcrypt, "bcrypt not installed")
@override_settings(PASSWORD_HASHERS=['django.contrib.auth.hashers.BCryptPasswordHasher'])
def test_bcrypt_harden_runtime(self):
hasher = get_hasher('bcrypt')
self.assertEqual('bcrypt', hasher.algorithm)
with mock.patch.object(hasher, 'rounds', 4):
encoded = make_password('letmein', hasher='bcrypt')
with mock.patch.object(hasher, 'rounds', 6), \
mock.patch.object(hasher, 'encode', side_effect=hasher.encode):
hasher.harden_runtime('wrong_password', encoded)
# Increasing rounds from 4 to 6 means an increase of 4 in workload,
# therefore hardening should run 3 times to make the timing the
# same (the original encode() call already ran once).
self.assertEqual(hasher.encode.call_count, 3)
# Get the original salt (includes the original workload factor)
algorithm, data = encoded.split('$', 1)
expected_call = (('wrong_password', data[:29].encode()),)
self.assertEqual(hasher.encode.call_args_list, [expected_call] * 3)
def test_unusable(self):
encoded = make_password(None)
self.assertEqual(len(encoded), len(UNUSABLE_PASSWORD_PREFIX) + UNUSABLE_PASSWORD_SUFFIX_LENGTH)
self.assertFalse(is_password_usable(encoded))
self.assertFalse(check_password(None, encoded))
self.assertFalse(check_password(encoded, encoded))
self.assertFalse(check_password(UNUSABLE_PASSWORD_PREFIX, encoded))
self.assertFalse(check_password('', encoded))
self.assertFalse(check_password('lètmein', encoded))
self.assertFalse(check_password('lètmeinz', encoded))
with self.assertRaisesMessage(ValueError, 'Unknown password hashing algorith'):
identify_hasher(encoded)
# Assert that the unusable passwords actually contain a random part.
# This might fail one day due to a hash collision.
self.assertNotEqual(encoded, make_password(None), "Random password collision?")
def test_unspecified_password(self):
"""
Makes sure specifying no plain password with a valid encoded password
returns `False`.
"""
self.assertFalse(check_password(None, make_password('lètmein')))
def test_bad_algorithm(self):
msg = (
"Unknown password hashing algorithm '%s'. Did you specify it in "
"the PASSWORD_HASHERS setting?"
)
with self.assertRaisesMessage(ValueError, msg % 'lolcat'):
make_password('lètmein', hasher='lolcat')
with self.assertRaisesMessage(ValueError, msg % 'lolcat'):
identify_hasher('lolcat$salt$hash')
def test_is_password_usable(self):
passwords = ('lètmein_badencoded', '', None)
for password in passwords:
with self.subTest(password=password):
self.assertIs(is_password_usable(password), True)
def test_low_level_pbkdf2(self):
hasher = PBKDF2PasswordHasher()
encoded = hasher.encode('lètmein', 'seasalt2')
self.assertEqual(encoded, 'pbkdf2_sha256$260000$seasalt2$UCGMhrOoaq1ghQPArIBK5RkI6IZLRxlIwHWA1dMy7y8=')
self.assertTrue(hasher.verify('lètmein', encoded))
def test_low_level_pbkdf2_sha1(self):
hasher = PBKDF2SHA1PasswordHasher()
encoded = hasher.encode('lètmein', 'seasalt2')
self.assertEqual(encoded, 'pbkdf2_sha1$260000$seasalt2$wAibXvW6jgvatCdONi6SMJ6q7mI=')
self.assertTrue(hasher.verify('lètmein', encoded))
@override_settings(
PASSWORD_HASHERS=[
'django.contrib.auth.hashers.PBKDF2PasswordHasher',
'django.contrib.auth.hashers.SHA1PasswordHasher',
'django.contrib.auth.hashers.MD5PasswordHasher',
],
)
def test_upgrade(self):
self.assertEqual('pbkdf2_sha256', get_hasher('default').algorithm)
for algo in ('sha1', 'md5'):
with self.subTest(algo=algo):
encoded = make_password('lètmein', hasher=algo)
state = {'upgraded': False}
def setter(password):
state['upgraded'] = True
self.assertTrue(check_password('lètmein', encoded, setter))
self.assertTrue(state['upgraded'])
def test_no_upgrade(self):
encoded = make_password('lètmein')
state = {'upgraded': False}
def setter():
state['upgraded'] = True
self.assertFalse(check_password('WRONG', encoded, setter))
self.assertFalse(state['upgraded'])
@override_settings(
PASSWORD_HASHERS=[
'django.contrib.auth.hashers.PBKDF2PasswordHasher',
'django.contrib.auth.hashers.SHA1PasswordHasher',
'django.contrib.auth.hashers.MD5PasswordHasher',
],
)
def test_no_upgrade_on_incorrect_pass(self):
self.assertEqual('pbkdf2_sha256', get_hasher('default').algorithm)
for algo in ('sha1', 'md5'):
with self.subTest(algo=algo):
encoded = make_password('lètmein', hasher=algo)
state = {'upgraded': False}
def setter():
state['upgraded'] = True
self.assertFalse(check_password('WRONG', encoded, setter))
self.assertFalse(state['upgraded'])
def test_pbkdf2_upgrade(self):
hasher = get_hasher('default')
self.assertEqual('pbkdf2_sha256', hasher.algorithm)
self.assertNotEqual(hasher.iterations, 1)
old_iterations = hasher.iterations
try:
# Generate a password with 1 iteration.
hasher.iterations = 1
encoded = make_password('letmein')
algo, iterations, salt, hash = encoded.split('$', 3)
self.assertEqual(iterations, '1')
state = {'upgraded': False}
def setter(password):
state['upgraded'] = True
# No upgrade is triggered
self.assertTrue(check_password('letmein', encoded, setter))
self.assertFalse(state['upgraded'])
# Revert to the old iteration count and ...
hasher.iterations = old_iterations
# ... check if the password would get updated to the new iteration count.
self.assertTrue(check_password('letmein', encoded, setter))
self.assertTrue(state['upgraded'])
finally:
hasher.iterations = old_iterations
def test_pbkdf2_harden_runtime(self):
hasher = get_hasher('default')
self.assertEqual('pbkdf2_sha256', hasher.algorithm)
with mock.patch.object(hasher, 'iterations', 1):
encoded = make_password('letmein')
with mock.patch.object(hasher, 'iterations', 6), \
mock.patch.object(hasher, 'encode', side_effect=hasher.encode):
hasher.harden_runtime('wrong_password', encoded)
# Encode should get called once ...
self.assertEqual(hasher.encode.call_count, 1)
# ... with the original salt and 5 iterations.
algorithm, iterations, salt, hash = encoded.split('$', 3)
expected_call = (('wrong_password', salt, 5),)
self.assertEqual(hasher.encode.call_args, expected_call)
def test_pbkdf2_upgrade_new_hasher(self):
hasher = get_hasher('default')
self.assertEqual('pbkdf2_sha256', hasher.algorithm)
self.assertNotEqual(hasher.iterations, 1)
state = {'upgraded': False}
def setter(password):
state['upgraded'] = True
with self.settings(PASSWORD_HASHERS=[
'auth_tests.test_hashers.PBKDF2SingleIterationHasher']):
encoded = make_password('letmein')
algo, iterations, salt, hash = encoded.split('$', 3)
self.assertEqual(iterations, '1')
# No upgrade is triggered
self.assertTrue(check_password('letmein', encoded, setter))
self.assertFalse(state['upgraded'])
# Revert to the old iteration count and check if the password would get
# updated to the new iteration count.
with self.settings(PASSWORD_HASHERS=[
'django.contrib.auth.hashers.PBKDF2PasswordHasher',
'auth_tests.test_hashers.PBKDF2SingleIterationHasher']):
self.assertTrue(check_password('letmein', encoded, setter))
self.assertTrue(state['upgraded'])
def test_check_password_calls_harden_runtime(self):
hasher = get_hasher('default')
encoded = make_password('letmein')
with mock.patch.object(hasher, 'harden_runtime'), \
mock.patch.object(hasher, 'must_update', return_value=True):
# Correct password supplied, no hardening needed
check_password('letmein', encoded)
self.assertEqual(hasher.harden_runtime.call_count, 0)
# Wrong password supplied, hardening needed
check_password('wrong_password', encoded)
self.assertEqual(hasher.harden_runtime.call_count, 1)
class BasePasswordHasherTests(SimpleTestCase):
not_implemented_msg = 'subclasses of BasePasswordHasher must provide %s() method'
def setUp(self):
self.hasher = BasePasswordHasher()
def test_load_library_no_algorithm(self):
msg = "Hasher 'BasePasswordHasher' doesn't specify a library attribute"
with self.assertRaisesMessage(ValueError, msg):
self.hasher._load_library()
def test_load_library_importerror(self):
PlainHasher = type('PlainHasher', (BasePasswordHasher,), {'algorithm': 'plain', 'library': 'plain'})
msg = "Couldn't load 'PlainHasher' algorithm library: No module named 'plain'"
with self.assertRaisesMessage(ValueError, msg):
PlainHasher()._load_library()
def test_attributes(self):
self.assertIsNone(self.hasher.algorithm)
self.assertIsNone(self.hasher.library)
def test_encode(self):
msg = self.not_implemented_msg % 'an encode'
with self.assertRaisesMessage(NotImplementedError, msg):
self.hasher.encode('password', 'salt')
def test_decode(self):
msg = self.not_implemented_msg % 'a decode'
with self.assertRaisesMessage(NotImplementedError, msg):
self.hasher.decode('encoded')
def test_harden_runtime(self):
msg = 'subclasses of BasePasswordHasher should provide a harden_runtime() method'
with self.assertWarnsMessage(Warning, msg):
self.hasher.harden_runtime('password', 'encoded')
def test_must_update(self):
self.assertIs(self.hasher.must_update('encoded'), False)
def test_safe_summary(self):
msg = self.not_implemented_msg % 'a safe_summary'
with self.assertRaisesMessage(NotImplementedError, msg):
self.hasher.safe_summary('encoded')
def test_verify(self):
msg = self.not_implemented_msg % 'a verify'
with self.assertRaisesMessage(NotImplementedError, msg):
self.hasher.verify('password', 'encoded')
@skipUnless(argon2, "argon2-cffi not installed")
@override_settings(PASSWORD_HASHERS=PASSWORD_HASHERS)
class TestUtilsHashPassArgon2(SimpleTestCase):
def test_argon2(self):
encoded = make_password('lètmein', hasher='argon2')
self.assertTrue(is_password_usable(encoded))
self.assertTrue(encoded.startswith('argon2$argon2id$'))
self.assertTrue(check_password('lètmein', encoded))
self.assertFalse(check_password('lètmeinz', encoded))
self.assertEqual(identify_hasher(encoded).algorithm, 'argon2')
# Blank passwords
blank_encoded = make_password('', hasher='argon2')
self.assertTrue(blank_encoded.startswith('argon2$argon2id$'))
self.assertTrue(is_password_usable(blank_encoded))
self.assertTrue(check_password('', blank_encoded))
self.assertFalse(check_password(' ', blank_encoded))
# Old hashes without version attribute
encoded = (
'argon2$argon2i$m=8,t=1,p=1$c29tZXNhbHQ$gwQOXSNhxiOxPOA0+PY10P9QFO'
'4NAYysnqRt1GSQLE55m+2GYDt9FEjPMHhP2Cuf0nOEXXMocVrsJAtNSsKyfg'
)
self.assertTrue(check_password('secret', encoded))
self.assertFalse(check_password('wrong', encoded))
# Old hashes with version attribute.
encoded = (
'argon2$argon2i$v=19$m=8,t=1,p=1$c2FsdHNhbHQ$YC9+jJCrQhs5R6db7LlN8Q'
)
self.assertIs(check_password('secret', encoded), True)
self.assertIs(check_password('wrong', encoded), False)
def test_argon2_decode(self):
salt = 'abcdefghijk'
encoded = make_password('lètmein', salt=salt, hasher='argon2')
hasher = get_hasher('argon2')
decoded = hasher.decode(encoded)
self.assertEqual(decoded['memory_cost'], hasher.memory_cost)
self.assertEqual(decoded['parallelism'], hasher.parallelism)
self.assertEqual(decoded['salt'], salt)
self.assertEqual(decoded['time_cost'], hasher.time_cost)
def test_argon2_upgrade(self):
self._test_argon2_upgrade('time_cost', 'time cost', 1)
self._test_argon2_upgrade('memory_cost', 'memory cost', 64)
self._test_argon2_upgrade('parallelism', 'parallelism', 1)
def test_argon2_version_upgrade(self):
hasher = get_hasher('argon2')
state = {'upgraded': False}
encoded = (
'argon2$argon2id$v=19$m=102400,t=2,p=8$Y041dExhNkljRUUy$TMa6A8fPJh'
'CAUXRhJXCXdw'
)
def setter(password):
state['upgraded'] = True
old_m = hasher.memory_cost
old_t = hasher.time_cost
old_p = hasher.parallelism
try:
hasher.memory_cost = 8
hasher.time_cost = 1
hasher.parallelism = 1
self.assertTrue(check_password('secret', encoded, setter, 'argon2'))
self.assertTrue(state['upgraded'])
finally:
hasher.memory_cost = old_m
hasher.time_cost = old_t
hasher.parallelism = old_p
def _test_argon2_upgrade(self, attr, summary_key, new_value):
hasher = get_hasher('argon2')
self.assertEqual('argon2', hasher.algorithm)
self.assertNotEqual(getattr(hasher, attr), new_value)
old_value = getattr(hasher, attr)
try:
# Generate hash with attr set to 1
setattr(hasher, attr, new_value)
encoded = make_password('letmein', hasher='argon2')
attr_value = hasher.safe_summary(encoded)[summary_key]
self.assertEqual(attr_value, new_value)
state = {'upgraded': False}
def setter(password):
state['upgraded'] = True
# No upgrade is triggered.
self.assertTrue(check_password('letmein', encoded, setter, 'argon2'))
self.assertFalse(state['upgraded'])
# Revert to the old rounds count and ...
setattr(hasher, attr, old_value)
# ... check if the password would get updated to the new count.
self.assertTrue(check_password('letmein', encoded, setter, 'argon2'))
self.assertTrue(state['upgraded'])
finally:
setattr(hasher, attr, old_value)