lib/python3.9/site-packages/IPython/terminal/tests/test_pt_inputhooks.py

import os
import importlib

import pytest

from IPython.terminal.pt_inputhooks import set_qt_api, get_inputhook_name_and_func


guis_avail = []


def _get_qt_vers():
    """If any version of Qt is available, this will populate `guis_avail` with 'qt' and 'qtx'. Due
    to the import mechanism, we can't import multiple versions of Qt in one session."""
    for gui in ["qt", "qt6", "qt5"]:
        print(f"Trying {gui}")
        try:
            set_qt_api(gui)
            importlib.import_module("IPython.terminal.pt_inputhooks.qt")
            guis_avail.append(gui)
            if "QT_API" in os.environ.keys():
                del os.environ["QT_API"]
        except ImportError:
            pass  # that version of Qt isn't available.
        except RuntimeError:
            pass  # the version of IPython doesn't know what to do with this Qt version.


_get_qt_vers()


@pytest.mark.skipif(
    len(guis_avail) == 0, reason="No viable version of PyQt or PySide installed."
)
def test_inputhook_qt():
    # Choose the "best" Qt version.
    gui_ret, _ = get_inputhook_name_and_func("qt")

    assert gui_ret != "qt"  # you get back the specific version that was loaded.
    assert gui_ret in guis_avail

    if len(guis_avail) > 2:
        # ...and now we're stuck with this version of Qt for good; can't switch.
        for not_gui in ["qt6", "qt5"]:
            if not_gui != gui_ret:
                break
        # Try to import the other gui; it won't work.
        gui_ret2, _ = get_inputhook_name_and_func(not_gui)
        assert gui_ret2 == gui_ret
        assert gui_ret2 != not_gui