diff --git a/tests/gui/__init__.py b/tests/gui/__init__.py
index c005824..061bf4a 100644
--- a/tests/gui/__init__.py
+++ b/tests/gui/__init__.py
@@ -13,13 +13,23 @@ from dangerzone.gui.updater import UpdaterThread
 from dangerzone.isolation_provider.dummy import Dummy
 
 
+def get_qt_app() -> Application:
+    if Application.instance() is None:
+        return Application()
+    else:
+        return Application.instance()
+
+
 def generate_isolated_updater(
     tmp_path: Path,
     monkeypatch: MonkeyPatch,
-    app_mocker: MockerFixture,
+    app_mocker: Optional[MockerFixture] = None,
 ) -> UpdaterThread:
     """Generate an Updater class with its own settings."""
-    app = app_mocker.MagicMock()
+    if app_mocker:
+        app = app_mocker.MagicMock()
+    else:
+        app = get_qt_app()
 
     dummy = Dummy()
     # XXX: We can monkey-patch global state without wrapping it in a context manager, or
@@ -38,3 +48,8 @@ def updater(
     tmp_path: Path, monkeypatch: MonkeyPatch, mocker: MockerFixture
 ) -> UpdaterThread:
     return generate_isolated_updater(tmp_path, monkeypatch, mocker)
+
+
+@pytest.fixture
+def qt_updater(tmp_path: Path, monkeypatch: MonkeyPatch) -> UpdaterThread:
+    return generate_isolated_updater(tmp_path, monkeypatch)
diff --git a/tests/gui/test_main_window.py b/tests/gui/test_main_window.py
new file mode 100644
index 0000000..2e04930
--- /dev/null
+++ b/tests/gui/test_main_window.py
@@ -0,0 +1,70 @@
+from pytest import MonkeyPatch
+from pytest_mock import MockerFixture
+from pytestqt.qtbot import QtBot
+
+from dangerzone.gui import MainWindow
+from dangerzone.gui import updater as updater_mod
+from dangerzone.gui.updater import UpdateReport, UpdaterThread
+from dangerzone.util import get_version
+
+from . import qt_updater, updater
+from .test_updater import default_updater_settings
+
+
+def test_qt(
+    qtbot: QtBot,
+    qt_updater: UpdaterThread,
+    monkeypatch: MonkeyPatch,
+    mocker: MockerFixture,
+) -> None:
+    updater = qt_updater
+    updater.dangerzone.settings.set("updater_check", True)
+    updater.dangerzone.settings.set("updater_last_check", 0)
+    expected_settings = default_updater_settings()
+    expected_settings["updater_check"] = True
+
+    mock_upstream_info = {"tag_name": f"v{get_version()}", "body": "changelog"}
+
+    # Always assume that we can perform multiple update checks in a row.
+    monkeypatch.setattr(updater, "_should_postpone_update_check", lambda: False)
+
+    # Make requests.get().json() return the above dictionary.
+    requests_mock = mocker.MagicMock()
+    requests_mock().json.return_value = mock_upstream_info
+    monkeypatch.setattr(updater_mod.requests, "get", requests_mock)
+
+    window = MainWindow(updater.dangerzone)
+    window.register_update_handler(updater.finished)
+    with qtbot.waitSignal(updater.finished) as blocker:
+        updater.start()
+
+    assert len(window.hamburger_button.menu().actions()) == 3
+    expected_settings["updater_last_check"] = updater.dangerzone.settings.get(
+        "updater_last_check"
+    )
+    assert updater.dangerzone.settings.get_updater_settings() == expected_settings
+
+    mock_upstream_info["tag_name"] = "v99.9.9"
+    mock_upstream_info["changelog"] = "changelog"
+    expected_settings["updater_latest_version"] = "99.9.9"
+    expected_settings["updater_latest_changelog"] = "<p>changelog</p>"
+
+    with qtbot.waitSignal(updater.finished) as blocker:
+        updater.start()
+
+    # The separator and install updates button has been added
+    assert len(window.hamburger_button.menu().actions()) == 5
+    expected_settings["updater_last_check"] = updater.dangerzone.settings.get(
+        "updater_last_check"
+    )
+    assert updater.dangerzone.settings.get_updater_settings() == expected_settings
+
+    # TODO:
+    # 1. Test that hamburger icon changes according to the update status.
+    # 2. Check that the dialogs for new updates / update errors have the expected
+    #    content.
+    # 3. Check that a user can toggle updates from the hamburger menu.
+    # 4. Check that errors are cleared from the settings, whenever we have a successful
+    #    update check.
+    # 5. Check that latest version/changelog, as well as update errors, are cached in
+    #    the settings