qt: Split machinery.init() and init_explicit() into two functions

This also moves the checking for sys.modules into _select_wrapper.

qutebrowser/qt/core.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtcore-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/dbus.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtdbus-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/gui.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtgui-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/machinery.py

@@ -139,6 +139,11 @@ def _select_wrapper(args: Optional[argparse.Namespace]) -> SelectionInfo:
     - Otherwise, if the QUTE_QT_WRAPPER environment variable is set, use that.
     - Otherwise, use PyQt5 (FIXME:qt6 autoselect).
     """
+    for name in WRAPPERS:
+        # If any Qt wrapper has been imported before this, all hope is lost.
+        if name in sys.modules:
+            raise Error(f"{name} already imported")
+
     if args is not None and args.qt_wrapper is not None:
         assert args.qt_wrapper in WRAPPERS, args.qt_wrapper  # ensured by argparse
         return SelectionInfo(wrapper=args.qt_wrapper, reason=SelectionReason.cli)
@@ -190,56 +195,24 @@ IS_PYSIDE: bool
 _initialized = False
 
 
-def init(args: Optional[argparse.Namespace] = None) -> SelectionInfo:
-    """Initialize Qt wrapper globals.
+def _set_globals(info: SelectionInfo) -> None:
+    """Set all global variables in this module based on the given SelectionInfo.
 
-    There is two ways how this function can be called:
-
-    - Explicitly, during qutebrowser startup, where it gets called before
-      earlyinit.early_init() in qutebrowser.py (i.e. after we have an argument
-      parser, but before any kinds of Qt usage). This allows `args` to be passed,
-      which is used to select the Qt wrapper (if --qt-wrapper is given).
-
-    - Implicitly, when any of the qutebrowser.qt.* modules in this package is imported.
-      This should never happen during normal qutebrowser usage, but means that any
-      qutebrowser module can be imported without having to worry about machinery.init().
-      This is useful for e.g. tests or manual interactive usage of the qutebrowser code.
-      In this case, `args` will be None.
+    Those are split into multiple global variables because that way we can teach mypy
+    about them via --always-true and --always-false, see tox.ini.
     """
     global INFO, USE_PYQT5, USE_PYQT6, USE_PYSIDE6, IS_QT5, IS_QT6, \
         IS_PYQT, IS_PYSIDE, _initialized
 
-    if args is None:
-        # Implicit initialization can happen multiple times
-        # (all subsequent calls are a no-op)
-        if _initialized:
-            return None  # FIXME:qt6
-    else:
-        # Explicit initialization can happen exactly once, and if it's used, there
-        # should not be any implicit initialization (qutebrowser.qt imports) before it.
-        if _initialized:  # pylint: disable=else-if-used
-            raise Error("init() already called before application init")
+    assert info.wrapper is not None, info
+    assert not _initialized
+
     _initialized = True
-
-    for name in WRAPPERS:
-        # If any Qt wrapper has been imported before this, all hope is lost.
-        if name in sys.modules:
-            raise Error(f"{name} already imported")
-
-    INFO = _select_wrapper(args)
-    if INFO.wrapper is None:
-        # No Qt wrapper was importable.
-        if args is None:
-            # Implicit initialization -> raise error immediately
-            raise NoWrapperAvailableError(INFO)
-        else:
-            # Explicit initialization -> show error in earlyinit.py
-            return INFO
-
-    USE_PYQT5 = INFO.wrapper == "PyQt5"
-    USE_PYQT6 = INFO.wrapper == "PyQt6"
-    USE_PYSIDE6 = INFO.wrapper == "PySide6"
-    assert USE_PYQT5 ^ USE_PYQT6 ^ USE_PYSIDE6
+    INFO = info
+    USE_PYQT5 = info.wrapper == "PyQt5"
+    USE_PYQT6 = info.wrapper == "PyQt6"
+    USE_PYSIDE6 = info.wrapper == "PySide6"
+    assert USE_PYQT5 + USE_PYQT6 + USE_PYSIDE6 == 1
 
     IS_QT5 = USE_PYQT5
     IS_QT6 = USE_PYQT6 or USE_PYSIDE6
@@ -248,4 +221,49 @@ def init(args: Optional[argparse.Namespace] = None) -> SelectionInfo:
     assert IS_QT5 ^ IS_QT6
     assert IS_PYQT ^ IS_PYSIDE
 
-    return INFO
+
+def init_implicit() -> None:
+    """Initialize Qt wrapper globals implicitly at Qt import time.
+
+    This gets called when any qutebrowser.qt module is imported, and implicitly
+    initializes the Qt wrapper globals.
+
+    After this is called, no explicit initialization via machinery.init() is possible
+    anymore - thus, this should never be called before init() when running qutebrowser
+    as an application (and any further calls will be a no-op).
+
+    However, this ensures that any qutebrowser module can be imported without
+    having to worry about machinery.init().  This is useful for e.g. tests or
+    manual interactive usage of the qutebrowser code.
+    """
+    if _initialized:
+        # Implicit initialization can happen multiple times
+        # (all subsequent calls are a no-op)
+        return None
+
+    info = _select_wrapper(args=None)
+    if info.wrapper is None:
+        raise NoWrapperAvailableError(info)
+
+    _set_globals(info)
+
+
+def init(args: argparse.Namespace) -> SelectionInfo:
+    """Initialize Qt wrapper globals during qutebrowser application start.
+
+    This gets called from earlyinit.py, i.e. after we have an argument parser,
+    but before any kinds of Qt usage. This allows `args` to be passed, which is
+    used to select the Qt wrapper (if --qt-wrapper is given).
+
+    If any qutebrowser.qt module is imported before this, init_implicit() will be called
+    instead, which means this can't be called anymore.
+    """
+    if _initialized:
+        raise Error("init() already called before application init")
+
+    info = _select_wrapper(args)
+    # If info is None here (no Qt wrapper available), we'll show an error later
+    # in earlyinit.py.
+
+    _set_globals(info)
+    return info

qutebrowser/qt/network.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtnetwork-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/opengl.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtopengl-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/printsupport.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtprintsupport-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/qml.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtqml-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/sip.py

@@ -16,7 +16,7 @@ Note that we don't yet abstract between PySide/PyQt here.
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 if machinery.USE_PYSIDE6:  # pylint: disable=no-else-raise
     raise machinery.Unavailable()

qutebrowser/qt/sql.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtsql-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/test.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qttest-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/webenginecore.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtwebenginecore-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/webenginewidgets.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtwebenginewidgets-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/webkit.py

@@ -15,7 +15,7 @@ https://qtwebkit.github.io/doc/qtwebkit/qtwebkit-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:  # pylint: disable=no-else-raise

qutebrowser/qt/webkitwidgets.py

@@ -15,7 +15,7 @@ https://qtwebkit.github.io/doc/qtwebkit/qtwebkitwidgets-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

qutebrowser/qt/widgets.py

@@ -14,7 +14,7 @@ https://doc.qt.io/qt-6/qtwidgets-index.html
 
 from qutebrowser.qt import machinery
 
-machinery.init()
+machinery.init_implicit()
 
 
 if machinery.USE_PYSIDE6:

tests/unit/test_qt_machinery.py

@@ -29,6 +29,15 @@ import pytest
 from qutebrowser.qt import machinery
 
 
+@pytest.fixture
+def undo_init(monkeypatch: pytest.MonkeyPatch) -> None:
+    """Pretend Qt support isn't initialized yet and Qt was never imported."""
+    monkeypatch.setattr(machinery, "_initialized", False)
+    monkeypatch.delenv("QUTE_QT_WRAPPER", raising=False)
+    for wrapper in machinery.WRAPPERS:
+        monkeypatch.delitem(sys.modules, wrapper, raising=False)
+
+
 @pytest.mark.parametrize(
     "exception",
     [
@@ -81,9 +90,10 @@ def test_selectioninfo_set_module():
                 "PyQt5: ImportError: Python imploded\n"
                 "PyQt6: success\n"
                 "selected: PyQt6 (via autoselect)"
-            )
+            ),
         ),
-    ])
+    ],
+)
 def test_selectioninfo_str(info: machinery.SelectionInfo, expected: str):
     assert str(info) == expected
 
@@ -236,6 +246,7 @@ def test_select_wrapper(
     env: Optional[str],
     expected: machinery.SelectionInfo,
     monkeypatch: pytest.MonkeyPatch,
+    undo_init: None,
 ):
     if env is None:
         monkeypatch.delenv("QUTE_QT_WRAPPER", raising=False)
@@ -245,109 +256,116 @@ def test_select_wrapper(
     assert machinery._select_wrapper(args) == expected
 
 
-@pytest.fixture
-def undo_init(monkeypatch: pytest.MonkeyPatch) -> None:
-    """Pretend Qt support isn't initialized yet and Qt was never imported."""
-    for wrapper in machinery.WRAPPERS:
-        monkeypatch.delitem(sys.modules, wrapper, raising=False)
-    monkeypatch.setattr(machinery, "_initialized", False)
-    monkeypatch.delenv("QUTE_QT_WRAPPER", raising=False)
-
-
-def test_init_multiple_implicit(monkeypatch: pytest.MonkeyPatch):
-    monkeypatch.setattr(machinery, "_initialized", True)
-    machinery.init()
-    machinery.init()
-
-
-def test_init_multiple_explicit(monkeypatch: pytest.MonkeyPatch):
-    monkeypatch.setattr(machinery, "_initialized", True)
-    machinery.init()
-
-    with pytest.raises(
-        machinery.Error, match=r"init\(\) already called before application init"
-    ):
-        machinery.init(args=argparse.Namespace(qt_wrapper="PyQt6"))
-
-
-def test_init_after_qt_import(monkeypatch: pytest.MonkeyPatch):
-    monkeypatch.setattr(machinery, "_initialized", False)
+def test_select_wrapper_after_qt_import():
+    assert any(wrapper in sys.modules for wrapper in machinery.WRAPPERS)
     with pytest.raises(machinery.Error, match="Py.* already imported"):
-        machinery.init()
+        machinery._select_wrapper(args=None)
 
 
-@pytest.mark.xfail(reason="autodetect not used yet")
-def test_init_none_available_implicit(
-    stubs: Any,
-    modules: Dict[str, bool],
-    monkeypatch: pytest.MonkeyPatch,
-    undo_init: None,
-):
-    stubs.ImportFake(modules, monkeypatch).patch()
-    message = "No Qt wrapper was importable."  # FIXME maybe check info too
-    with pytest.raises(machinery.NoWrapperAvailableError, match=message):
-        machinery.init(args=None)
+class TestInit:
+    @pytest.fixture
+    def empty_args(self) -> argparse.Namespace:
+        return argparse.Namespace(qt_wrapper=None)
 
+    def test_multiple_implicit(self, monkeypatch: pytest.MonkeyPatch):
+        monkeypatch.setattr(machinery, "_initialized", True)
+        machinery.init_implicit()
+        machinery.init_implicit()
 
-@pytest.mark.xfail(reason="autodetect not used yet")
-def test_init_none_available_explicit(
-    stubs: Any,
-    modules: Dict[str, bool],
-    monkeypatch: pytest.MonkeyPatch,
-    undo_init: None,
-):
-    stubs.ImportFake(modules, monkeypatch).patch()
-    info = machinery.init(args=argparse.Namespace(qt_wrapper=None))
-    assert info == machinery.SelectionInfo(
-        wrapper=None,
-        reason=machinery.SelectionReason.default,
-        pyqt6="ImportError: Fake ImportError for PyQt6.",
-        pyqt5="ImportError: Fake ImportError for PyQt5.",
+    def test_multiple_explicit(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+        empty_args: argparse.Namespace,
+    ):
+        monkeypatch.setattr(machinery, "_initialized", True)
+
+        with pytest.raises(
+            machinery.Error, match=r"init\(\) already called before application init"
+        ):
+            machinery.init(args=empty_args)
+
+    @pytest.mark.xfail(reason="autodetect not used yet")
+    def test_none_available_implicit(
+        self,
+        stubs: Any,
+        modules: Dict[str, bool],
+        monkeypatch: pytest.MonkeyPatch,
+        undo_init: None,
+    ):
+        stubs.ImportFake(modules, monkeypatch).patch()
+        message = "No Qt wrapper was importable."  # FIXME maybe check info too
+        with pytest.raises(machinery.NoWrapperAvailableError, match=message):
+            machinery.init_implicit()
+
+    @pytest.mark.xfail(reason="autodetect not used yet")
+    def test_none_available_explicit(
+        self,
+        stubs: Any,
+        modules: Dict[str, bool],
+        monkeypatch: pytest.MonkeyPatch,
+        empty_args: argparse.Namespace,
+        undo_init: None,
+    ):
+        stubs.ImportFake(modules, monkeypatch).patch()
+        info = machinery.init(args=empty_args)
+        assert info == machinery.SelectionInfo(
+            wrapper=None,
+            reason=machinery.SelectionReason.default,
+            pyqt6="ImportError: Fake ImportError for PyQt6.",
+            pyqt5="ImportError: Fake ImportError for PyQt5.",
+        )
+
+    @pytest.mark.parametrize(
+        "selected_wrapper, true_vars",
+        [
+            ("PyQt6", ["USE_PYQT6", "IS_QT6", "IS_PYQT"]),
+            ("PyQt5", ["USE_PYQT5", "IS_QT5", "IS_PYQT"]),
+            ("PySide6", ["USE_PYSIDE6", "IS_QT6", "IS_PYSIDE"]),
+        ],
     )
+    @pytest.mark.parametrize("explicit", [True, False])
+    def test_properly(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+        selected_wrapper: str,
+        true_vars: str,
+        explicit: bool,
+        empty_args: argparse.Namespace,
+        undo_init: None,
+    ):
+        bool_vars = [
+            "USE_PYQT5",
+            "USE_PYQT6",
+            "USE_PYSIDE6",
+            "IS_QT5",
+            "IS_QT6",
+            "IS_PYQT",
+            "IS_PYSIDE",
+        ]
+        all_vars = bool_vars + ["INFO"]
+        # Make sure we didn't forget anything that's declared in the module.
+        # Not sure if this is a good idea. Might remove it in the future if it breaks.
+        assert set(typing.get_type_hints(machinery).keys()) == set(all_vars)
 
+        for var in all_vars:
+            monkeypatch.delattr(machinery, var)
 
-@pytest.mark.parametrize(
-    "selected_wrapper, true_vars",
-    [
-        ("PyQt6", ["USE_PYQT6", "IS_QT6", "IS_PYQT"]),
-        ("PyQt5", ["USE_PYQT5", "IS_QT5", "IS_PYQT"]),
-        ("PySide6", ["USE_PYSIDE6", "IS_QT6", "IS_PYSIDE"]),
-    ],
-)
-def test_init_properly(
-    monkeypatch: pytest.MonkeyPatch,
-    selected_wrapper: str,
-    true_vars: str,
-    undo_init: None,
-):
-    bool_vars = [
-        "USE_PYQT5",
-        "USE_PYQT6",
-        "USE_PYSIDE6",
-        "IS_QT5",
-        "IS_QT6",
-        "IS_PYQT",
-        "IS_PYSIDE",
-    ]
-    all_vars = bool_vars + ["INFO"]
-    # Make sure we didn't forget anything that's declared in the module.
-    # Not sure if this is a good idea. Might remove it in the future if it breaks.
-    assert set(typing.get_type_hints(machinery).keys()) == set(all_vars)
+        info = machinery.SelectionInfo(
+            wrapper=selected_wrapper,
+            reason=machinery.SelectionReason.fake,
+        )
+        monkeypatch.setattr(machinery, "_select_wrapper", lambda args: info)
 
-    for var in all_vars:
-        monkeypatch.delattr(machinery, var)
+        if explicit:
+            ret = machinery.init(empty_args)
+            assert ret == info
+        else:
+            machinery.init_implicit()
 
-    info = machinery.SelectionInfo(
-        wrapper=selected_wrapper,
-        reason=machinery.SelectionReason.fake,
-    )
-    monkeypatch.setattr(machinery, "_select_wrapper", lambda args: info)
+        assert machinery.INFO == info
 
-    machinery.init()
-    assert machinery.INFO == info
+        expected_vars = dict.fromkeys(bool_vars, False)
+        expected_vars.update(dict.fromkeys(true_vars, True))
+        actual_vars = {var: getattr(machinery, var) for var in bool_vars}
 
-    expected_vars = dict.fromkeys(bool_vars, False)
-    expected_vars.update(dict.fromkeys(true_vars, True))
-    actual_vars = {var: getattr(machinery, var) for var in bool_vars}
-
-    assert expected_vars == actual_vars
+        assert expected_vars == actual_vars