import unittest
from unittest.mock import patch
from server_buddy.core.startup import desktop_error

class StartupTests(unittest.TestCase):
    @patch('server_buddy.core.startup.sys.platform', 'linux')
    @patch.dict('os.environ', {'DISPLAY': ':0', 'QT_QPA_PLATFORM': 'xcb'}, clear=True)
    @patch('server_buddy.core.startup.ctypes.CDLL', side_effect=OSError)
    def test_missing_xcb_returns_install_instruction(self, loader):
        self.assertIn('sudo apt install libxcb-cursor0', desktop_error())

    @patch('server_buddy.core.startup.sys.platform', 'linux')
    @patch.dict('os.environ', {'QT_QPA_PLATFORM': 'offscreen'}, clear=True)
    @patch('server_buddy.core.startup.ctypes.CDLL')
    def test_offscreen_does_not_require_xcb(self, loader):
        self.assertIsNone(desktop_error())
        loader.assert_not_called()