import unittest

from app.tzsp import TZSPError, decode_tzsp


class TZSPTests(unittest.TestCase):
    def test_decodes_ethernet_frame(self):
        frame = b"\xaa" * 60
        packet = decode_tzsp(b"\x01\x00\x00\x01\x01" + frame)
        self.assertEqual(packet.encapsulation, 1)
        self.assertEqual(packet.frame, frame)

    def test_skips_tags(self):
        frame = b"\xbb" * 60
        data = b"\x01\x00\x00\x01" + b"\x0a\x02\x12\x34" + b"\x00" + b"\x01" + frame
        packet = decode_tzsp(data)
        self.assertEqual(packet.frame, frame)

    def test_rejects_missing_end_tag(self):
        with self.assertRaises(TZSPError):
            decode_tzsp(b"\x01\x00\x00\x01\x0a\x01\xff")

    def test_rejects_non_packet_type(self):
        with self.assertRaises(TZSPError):
            decode_tzsp(b"\x01\x03\x00\x01\x01\x00")


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