Add diagnostics to LaMetric (#79757)

* Add diagnostics to LaMetric

* Add return value typing

Co-authored-by: Martin Hjelmare <marhje52@gmail.com>

homeassistant/components/lametric/diagnostics.py

@@ -0,0 +1,29 @@
+"""Diagnostics support for LaMetric."""
+from __future__ import annotations
+
+import json
+from typing import Any
+
+from homeassistant.components.diagnostics import async_redact_data
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.core import HomeAssistant
+
+from .const import DOMAIN
+from .coordinator import LaMetricDataUpdateCoordinator
+
+TO_REDACT = {
+    "device_id",
+    "name",
+    "serial_number",
+    "ssid",
+}
+
+
+async def async_get_config_entry_diagnostics(
+    hass: HomeAssistant, entry: ConfigEntry
+) -> dict[str, Any]:
+    """Return diagnostics for a config entry."""
+    coordinator: LaMetricDataUpdateCoordinator = hass.data[DOMAIN][entry.entry_id]
+    # Round-trip via JSON to trigger serialization
+    data = json.loads(coordinator.data.json())
+    return async_redact_data(data, TO_REDACT)