Move connect_single to SmartDevice.connect (#538)

This refactors `Discover.connect_single` by moving device instance construction into a separate device factory module.
New `SmartDevice.connect(host, *, port, timeout, credentials, device_type)` class method replaces the functionality of `connect_single`,
and also now allows constructing device instances without relying on UDP discovery for type discovery if `device_type` parameter is set.

---------

Co-authored-by: Teemu R. <tpr@iki.fi>

kasa/tests/test_device_factory.py

@@ -0,0 +1,74 @@
+# type: ignore
+import logging
+from typing import Type
+
+import pytest  # type: ignore # https://github.com/pytest-dev/pytest/issues/3342
+
+from kasa import (
+    DeviceType,
+    SmartBulb,
+    SmartDevice,
+    SmartDeviceException,
+    SmartDimmer,
+    SmartLightStrip,
+    SmartPlug,
+)
+from kasa.device_factory import connect
+
+
+@pytest.mark.parametrize("custom_port", [123, None])
+async def test_connect(discovery_data: dict, mocker, custom_port):
+    """Make sure that connect returns an initialized SmartDevice instance."""
+    host = "127.0.0.1"
+    mocker.patch("kasa.TPLinkSmartHomeProtocol.query", return_value=discovery_data)
+
+    dev = await connect(host, port=custom_port)
+    assert issubclass(dev.__class__, SmartDevice)
+    assert dev.port == custom_port or dev.port == 9999
+
+
+@pytest.mark.parametrize("custom_port", [123, None])
+@pytest.mark.parametrize(
+    ("device_type", "klass"),
+    (
+        (DeviceType.Plug, SmartPlug),
+        (DeviceType.Bulb, SmartBulb),
+        (DeviceType.Dimmer, SmartDimmer),
+        (DeviceType.LightStrip, SmartLightStrip),
+        (DeviceType.Unknown, SmartDevice),
+    ),
+)
+async def test_connect_passed_device_type(
+    discovery_data: dict,
+    mocker,
+    device_type: DeviceType,
+    klass: Type[SmartDevice],
+    custom_port,
+):
+    """Make sure that connect with a passed device type."""
+    host = "127.0.0.1"
+    mocker.patch("kasa.TPLinkSmartHomeProtocol.query", return_value=discovery_data)
+
+    dev = await connect(host, port=custom_port, device_type=device_type)
+    assert isinstance(dev, klass)
+    assert dev.port == custom_port or dev.port == 9999
+
+
+async def test_connect_query_fails(discovery_data: dict, mocker):
+    """Make sure that connect fails when query fails."""
+    host = "127.0.0.1"
+    mocker.patch("kasa.TPLinkSmartHomeProtocol.query", side_effect=SmartDeviceException)
+
+    with pytest.raises(SmartDeviceException):
+        await connect(host)
+
+
+async def test_connect_logs_connect_time(
+    discovery_data: dict, caplog: pytest.LogCaptureFixture, mocker
+):
+    """Test that the connect time is logged when debug logging is enabled."""
+    host = "127.0.0.1"
+    mocker.patch("kasa.TPLinkSmartHomeProtocol.query", return_value=discovery_data)
+    logging.getLogger("kasa").setLevel(logging.DEBUG)
+    await connect(host)
+    assert "seconds to connect" in caplog.text