django/tests/test_runner/test_shuffler.py

from unittest import mock

from django.test import SimpleTestCase
from django.test.runner import Shuffler


class ShufflerTests(SimpleTestCase):

    def test_hash_text(self):
        actual = Shuffler._hash_text('abcd')
        self.assertEqual(actual, 'e2fc714c4727ee9395f324cd2e7f331f')

    def test_hash_text_hash_algorithm(self):
        class MyShuffler(Shuffler):
            hash_algorithm = 'sha1'

        actual = MyShuffler._hash_text('abcd')
        self.assertEqual(actual, '81fe8bfe87576c3ecb22426f8e57847382917acf')

    def test_init(self):
        shuffler = Shuffler(100)
        self.assertEqual(shuffler.seed, 100)
        self.assertEqual(shuffler.seed_source, 'given')

    def test_init_none_seed(self):
        with mock.patch('random.randint', return_value=200):
            shuffler = Shuffler(None)
        self.assertEqual(shuffler.seed, 200)
        self.assertEqual(shuffler.seed_source, 'generated')

    def test_init_no_seed_argument(self):
        with mock.patch('random.randint', return_value=300):
            shuffler = Shuffler()
        self.assertEqual(shuffler.seed, 300)
        self.assertEqual(shuffler.seed_source, 'generated')

    def test_seed_display(self):
        shuffler = Shuffler(100)
        shuffler.seed_source = 'test'
        self.assertEqual(shuffler.seed_display, '100 (test)')

    def test_hash_item_seed(self):
        cases = [
            (1234, '64ad3fb166ddb41a2ca24f1803b8b722'),
            # Passing a string gives the same value.
            ('1234', '64ad3fb166ddb41a2ca24f1803b8b722'),
            (5678, '4dde450ad339b6ce45a0a2666e35b975'),
        ]
        for seed, expected in cases:
            with self.subTest(seed=seed):
                shuffler = Shuffler(seed=seed)
                actual = shuffler._hash_item('abc', lambda x: x)
                self.assertEqual(actual, expected)

    def test_hash_item_key(self):
        cases = [
            (lambda x: x, '64ad3fb166ddb41a2ca24f1803b8b722'),
            (lambda x: x.upper(), 'ee22e8597bff91742affe4befbf4649a'),
        ]
        for key, expected in cases:
            with self.subTest(key=key):
                shuffler = Shuffler(seed=1234)
                actual = shuffler._hash_item('abc', key)
                self.assertEqual(actual, expected)

    def test_shuffle_key(self):
        cases = [
            (lambda x: x, ['a', 'd', 'b', 'c']),
            (lambda x: x.upper(), ['d', 'c', 'a', 'b']),
        ]
        for num, (key, expected) in enumerate(cases, start=1):
            with self.subTest(num=num):
                shuffler = Shuffler(seed=1234)
                actual = shuffler.shuffle(['a', 'b', 'c', 'd'], key)
                self.assertEqual(actual, expected)

    def test_shuffle_consistency(self):
        seq = [str(n) for n in range(5)]
        cases = [
            (None, ['3', '0', '2', '4', '1']),
            (0, ['3', '2', '4', '1']),
            (1, ['3', '0', '2', '4']),
            (2, ['3', '0', '4', '1']),
            (3, ['0', '2', '4', '1']),
            (4, ['3', '0', '2', '1']),
        ]
        shuffler = Shuffler(seed=1234)
        for index, expected in cases:
            with self.subTest(index=index):
                if index is None:
                    new_seq = seq
                else:
                    new_seq = seq.copy()
                    del new_seq[index]
                actual = shuffler.shuffle(new_seq, lambda x: x)
                self.assertEqual(actual, expected)

    def test_shuffle_same_hash(self):
        shuffler = Shuffler(seed=1234)
        msg = "item 'A' has same hash 'a56ce89262959e151ee2266552f1819c' as item 'a'"
        with self.assertRaisesMessage(RuntimeError, msg):
            shuffler.shuffle(['a', 'b', 'A'], lambda x: x.upper())