import unittest
from example import brackets_error


class LinearTests(unittest.TestCase):
    def test_nested_and_text(self):
        self.assertIsNone(brackets_error(''))
        self.assertIsNone(brackets_error('a[({x})]'))
        self.assertEqual(brackets_error('([)]'), 2)

    def test_unmatched(self):
        self.assertEqual(brackets_error(']'), 0)
        self.assertEqual(brackets_error('(['), 1)
        self.assertIsNone(brackets_error('(' * 10000 + ')' * 10000))


if __name__ == '__main__':
    unittest.main()