Listen for dbus property changes (#3872)

* Listen for dbus property changes

* Avoid remaking dbus proxy objects

* proper snake case for pylint

* some cleanup and more tests

tests/dbus/test_interface.py

@@ -0,0 +1,92 @@
+"""Test dbus interface."""
+
+import asyncio
+from dataclasses import dataclass
+from unittest.mock import MagicMock
+
+from dbus_next.aio.message_bus import MessageBus
+import pytest
+
+from supervisor.dbus.interface import DBusInterface, DBusInterfaceProxy
+
+from tests.common import fire_property_change_signal, fire_watched_signal
+
+
+@dataclass
+class DBusInterfaceMock:
+    """DBus Interface and signalling mocks."""
+
+    obj: DBusInterface
+    on_device_added: MagicMock = MagicMock()
+    off_device_added: MagicMock = MagicMock()
+
+
+@pytest.fixture(name="proxy")
+async def fixture_proxy(
+    request: pytest.FixtureRequest, dbus_bus: MessageBus, dbus
+) -> DBusInterfaceMock:
+    """Get a proxy."""
+    proxy = DBusInterfaceProxy()
+    proxy.bus_name = "org.freedesktop.NetworkManager"
+    proxy.object_path = "/org/freedesktop/NetworkManager"
+    proxy.properties_interface = "org.freedesktop.NetworkManager"
+    proxy.sync_properties = request.param
+
+    await proxy.connect(dbus_bus)
+
+    # pylint: disable=protected-access
+    nm_proxy = proxy.dbus._proxies["org.freedesktop.NetworkManager"]
+
+    mock = DBusInterfaceMock(proxy)
+    setattr(nm_proxy, "on_device_added", mock.on_device_added)
+    setattr(nm_proxy, "off_device_added", mock.off_device_added)
+
+    yield mock
+
+
+@pytest.mark.parametrize("proxy", [True], indirect=True)
+async def test_dbus_proxy_connect(dbus_bus: MessageBus, proxy: DBusInterfaceMock):
+    """Test dbus proxy connect."""
+    assert proxy.obj.is_connected
+    assert proxy.obj.properties["Connectivity"] == 4
+
+    fire_property_change_signal(proxy.obj, {"Connectivity": 1})
+    await asyncio.sleep(0)
+    assert proxy.obj.properties["Connectivity"] == 1
+
+
+@pytest.mark.parametrize("proxy", [False], indirect=True)
+async def test_dbus_proxy_connect_no_sync(
+    dbus_bus: MessageBus, proxy: DBusInterfaceMock
+):
+    """Test dbus proxy connect with no properties sync."""
+    assert proxy.obj.is_connected
+    assert proxy.obj.properties["Connectivity"] == 4
+
+    with pytest.raises(AssertionError):
+        fire_property_change_signal(proxy.obj, {"Connectivity": 1})
+
+
+@pytest.mark.parametrize("proxy", [False], indirect=True)
+async def test_signal_listener_disconnect(
+    dbus_bus: MessageBus, proxy: DBusInterfaceMock
+):
+    """Test disconnect/delete unattaches signal listeners."""
+    assert proxy.obj.is_connected
+    device = None
+
+    async def callback(dev: str):
+        nonlocal device
+        device = dev
+
+    proxy.obj.dbus.on_device_added(callback)
+    proxy.on_device_added.assert_called_once_with(callback)
+
+    fire_watched_signal(
+        proxy.obj, "org.freedesktop.NetworkManager.DeviceAdded", ["/test/obj/1"]
+    )
+    await asyncio.sleep(0)
+    assert device == "/test/obj/1"
+
+    proxy.obj.disconnect()
+    proxy.off_device_added.assert_called_once_with(callback)