import pytest
from unittest.mock import patch, MagicMock
import serial
from m2m.serial.serial_port import SerialPort
from m2m.exceptions import SerialError

def test_serial_port_standard():
    with patch('serial.serial_for_url') as mock_for_url:
        mock_serial = MagicMock()
        mock_for_url.return_value = mock_serial
        
        with SerialPort(port='/dev/ttyUSB0', baudrate=115200) as sp:
            mock_for_url.assert_called_once_with(
                url='/dev/ttyUSB0',
                baudrate=115200,
                timeout=1.0
            )

def test_serial_port_tcp_url():
    with patch('serial.serial_for_url') as mock_for_url:
        mock_serial = MagicMock()
        mock_for_url.return_value = mock_serial
        
        url = 'socket://1.2.3.4:5678'
        with SerialPort(port=url, baudrate=9600) as sp:
            mock_for_url.assert_called_once_with(
                url=url,
                baudrate=9600,
                timeout=1.0
            )

def test_serial_port_invalid_url():
    with patch('serial.serial_for_url') as mock_for_url:
        mock_for_url.side_effect = ValueError("invalid URL")
        
        with pytest.raises(SerialError) as excinfo:
            SerialPort(port='invalid://port')
        assert "Could not open invalid://port" in str(excinfo.value)

def test_serial_port_mock():
    # Verify 'MOCK' still uses MockSerial and NOT serial_for_url
    with patch('m2m.serial.serial_port.MockSerial') as mock_mock:
        with patch('serial.serial_for_url') as mock_for_url:
            sp = SerialPort(port='MOCK')
            mock_mock.assert_called_once()
            mock_for_url.assert_not_called()