"""Python 3.10+; run this file to execute its round-trip tests."""
import csv
import io
import unittest


def encode(rows):
    stream = io.StringIO(newline="")
    csv.writer(stream, lineterminator="\r\n").writerows(rows)
    return stream.getvalue()


def decode(text):
    return list(csv.reader(io.StringIO(text, newline=""), strict=True))


class RoundTripTests(unittest.TestCase):
    def test_round_trip(self):
        rows = [["name", "note"], ["Ada, Jr.", 'says "hello"'],
                ["雪", "line one\nline two"], ["", ""]]
        self.assertEqual(decode(encode(rows)), rows)

    def test_split_is_not_a_parser(self):
        self.assertEqual(len('"Ada, Jr.",ok'.split(",")), 3)
        self.assertEqual(len(decode('"Ada, Jr.",ok')[0]), 2)

    def test_none_needs_an_application_policy(self):
        self.assertEqual(decode(encode([[None, ""]])), [["", ""]])


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