Various test code cleanups (#725)

* Separate fake protocols for iot and smart

* Move control_child impl into its own method

* Organize schemas into correct places

* Add test_childdevice

* Add missing return for _handle_control_child

kasa/tests/test_childdevice.py

@@ -0,0 +1,31 @@
+from kasa.smartprotocol import _ChildProtocolWrapper
+from kasa.tapo import ChildDevice
+
+from .conftest import strip_smart
+
+
+@strip_smart
+def test_childdevice_init(dev, dummy_protocol, mocker):
+    """Test that child devices get initialized and use protocol wrapper."""
+    assert len(dev.children) > 0
+    assert dev.is_strip
+
+    first = dev.children[0]
+    assert isinstance(first.protocol, _ChildProtocolWrapper)
+
+    assert first._info["category"] == "plug.powerstrip.sub-plug"
+    assert "position" in first._info
+
+
+@strip_smart
+async def test_childdevice_update(dev, dummy_protocol, mocker):
+    """Test that parent update updates children."""
+    assert len(dev.children) > 0
+    first = dev.children[0]
+
+    child_update = mocker.patch.object(first, "update")
+    await dev.update()
+    child_update.assert_called()
+
+    assert dev._last_update != first._last_update
+    assert dev._last_update["child_info"]["child_device_list"][0] == first._last_update