import unittest
from unittest.util import safe_repr, sorted_list_difference, unorderable_list_difference


class TestUtil(unittest.TestCase):
    def test_safe_repr(self):
        class RaisingRepr:
            def __repr__(self):
                raise ValueError("Invalid repr()")

        class LongRepr:
            def __repr__(self):
                return 'x' * 100

        safe_repr(RaisingRepr())
        self.assertEqual(safe_repr('foo'), "'foo'")
        self.assertEqual(safe_repr(LongRepr(), short=True), 'x'*80 + ' [truncated]...')

    def test_sorted_list_difference(self):
        self.assertEqual(sorted_list_difference([], []), ([], []))
        self.assertEqual(sorted_list_difference([1, 2], [2, 3]), ([1], [3]))
        self.assertEqual(sorted_list_difference([1, 2], [1, 3]), ([2], [3]))
        self.assertEqual(sorted_list_difference([1, 1, 1], [1, 2, 3]), ([], [2, 3]))
        self.assertEqual(sorted_list_difference([4], [1, 2, 3, 4]), ([], [1, 2, 3]))
        self.assertEqual(sorted_list_difference([1, 1], [2]), ([1], [2]))
        self.assertEqual(sorted_list_difference([2], [1, 1]), ([2], [1]))
        self.assertEqual(sorted_list_difference([1, 2], [1, 1]), ([2], []))

    def test_sorted_list_difference_tail_deduplication(self):
        # Tail deduplication when one list is exhausted before the other.
        # These exercise the except-IndexError path in sorted_list_difference.
        self.assertEqual(sorted_list_difference([], [0, 0]), ([], [0]))
        self.assertEqual(sorted_list_difference([0, 0], []), ([0], []))
        self.assertEqual(sorted_list_difference([], [1, 1, 2, 2]), ([], [1, 2]))
        self.assertEqual(sorted_list_difference([1, 1, 2, 2], []), ([1, 2], []))
        # One list exhausts mid-way, leaving duplicated tail in the other.
        self.assertEqual(sorted_list_difference([1], [1, 2, 2, 3, 3]), ([], [2, 3]))
        self.assertEqual(sorted_list_difference([1, 2, 2, 3, 3], [1]), ([2, 3], []))

    def test_sorted_list_difference_strings(self):
        self.assertEqual(
            sorted_list_difference(['a', 'b'], ['b', 'c']),
            (['a'], ['c']))
        self.assertEqual(
            sorted_list_difference([], ['a', 'a', 'b']),
            ([], ['a', 'b']))
        self.assertEqual(
            sorted_list_difference(['a', 'a', 'b'], []),
            (['a', 'b'], []))

    def test_sorted_list_difference_unhashable(self):
        self.assertEqual(
            sorted_list_difference([[1], [2]], [[2], [3]]),
            ([[1]], [[3]]))
        self.assertEqual(
            sorted_list_difference([], [[0], [0]]),
            ([], [[0]]))
        self.assertEqual(
            sorted_list_difference([[0], [0]], []),
            ([[0]], []))

    def test_unorderable_list_difference(self):
        self.assertEqual(unorderable_list_difference([], []), ([], []))
        self.assertEqual(unorderable_list_difference([1, 2], []), ([2, 1], []))
        self.assertEqual(unorderable_list_difference([], [1, 2]), ([], [1, 2]))
        self.assertEqual(unorderable_list_difference([1, 2], [1, 3]), ([2], [3]))