Add diagnostics platform to DSMR Reader (#115805)

* Add diagnostics platform

* Feedback

---------

Co-authored-by: Joost Lekkerkerker <joostlek@outlook.com>

homeassistant/components/dsmr_reader/diagnostics.py

@@ -0,0 +1,27 @@
+"""Diagnostics support for DSMR Reader."""
+
+from __future__ import annotations
+
+from typing import Any
+
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.core import HomeAssistant
+from homeassistant.helpers import entity_registry as er
+
+
+async def async_get_config_entry_diagnostics(
+    hass: HomeAssistant, entry: ConfigEntry
+) -> dict[str, Any]:
+    """Return diagnostics for the config entry."""
+    ent_reg = er.async_get(hass)
+    entities = [
+        entity.entity_id
+        for entity in er.async_entries_for_config_entry(ent_reg, entry.entry_id)
+    ]
+
+    entity_states = {entity: hass.states.get(entity) for entity in entities}
+
+    return {
+        "entry": entry.as_dict(),
+        "entities": entity_states,
+    }

tests/components/dsmr_reader/snapshots/test_diagnostics.ambr

@@ -0,0 +1,23 @@
+# serializer version: 1
+# name: test_get_config_entry_diagnostics
+  dict({
+    'entities': dict({
+    }),
+    'entry': dict({
+      'data': dict({
+      }),
+      'disabled_by': None,
+      'domain': 'dsmr_reader',
+      'entry_id': 'TEST_ENTRY_ID',
+      'minor_version': 1,
+      'options': dict({
+      }),
+      'pref_disable_new_entities': False,
+      'pref_disable_polling': False,
+      'source': 'user',
+      'title': 'dsmr_reader',
+      'unique_id': 'UNIQUE_TEST_ID',
+      'version': 1,
+    }),
+  })
+# ---

tests/components/dsmr_reader/test_diagnostics.py

@@ -0,0 +1,39 @@
+"""Test the DSMR Reader component diagnostics."""
+
+from unittest.mock import patch
+
+from syrupy import SnapshotAssertion
+
+from homeassistant.components.dsmr_reader.const import DOMAIN
+from homeassistant.core import HomeAssistant
+
+from tests.common import MockConfigEntry
+from tests.components.diagnostics import get_diagnostics_for_config_entry
+from tests.typing import ClientSessionGenerator
+
+
+async def test_get_config_entry_diagnostics(
+    hass: HomeAssistant,
+    snapshot: SnapshotAssertion,
+    hass_client: ClientSessionGenerator,
+) -> None:
+    """Test if get_config_entry_diagnostics returns the correct data."""
+    config_entry = MockConfigEntry(
+        domain=DOMAIN,
+        title=DOMAIN,
+        options={},
+        entry_id="TEST_ENTRY_ID",
+        unique_id="UNIQUE_TEST_ID",
+    )
+    config_entry.add_to_hass(hass)
+
+    with patch(
+        "homeassistant.components.dsmr_reader.async_setup_entry", return_value=True
+    ):
+        await hass.config_entries.async_setup(config_entry.entry_id)
+        await hass.async_block_till_done()
+
+    diagnostics = await get_diagnostics_for_config_entry(
+        hass, hass_client, config_entry
+    )
+    assert diagnostics == snapshot