Add Saunum integration (#155099)

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

CODEOWNERS

@@ -1376,6 +1376,8 @@ build.json @home-assistant/supervisor
 /tests/components/sanix/ @tomaszsluszniak
 /homeassistant/components/satel_integra/ @Tommatheussen
 /tests/components/satel_integra/ @Tommatheussen
+/homeassistant/components/saunum/ @mettolen
+/tests/components/saunum/ @mettolen
 /homeassistant/components/scene/ @home-assistant/core
 /tests/components/scene/ @home-assistant/core
 /homeassistant/components/schedule/ @home-assistant/core

homeassistant/components/saunum/__init__.py

@@ -0,0 +1,50 @@
+"""The Saunum Leil Sauna Control Unit integration."""
+
+from __future__ import annotations
+
+import logging
+
+from pysaunum import SaunumClient, SaunumConnectionError
+
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.const import CONF_HOST
+from homeassistant.core import HomeAssistant
+from homeassistant.exceptions import ConfigEntryNotReady
+
+from .const import PLATFORMS
+from .coordinator import LeilSaunaCoordinator
+
+_LOGGER = logging.getLogger(__name__)
+
+type LeilSaunaConfigEntry = ConfigEntry[LeilSaunaCoordinator]
+
+
+async def async_setup_entry(hass: HomeAssistant, entry: LeilSaunaConfigEntry) -> bool:
+    """Set up Saunum Leil Sauna from a config entry."""
+    host = entry.data[CONF_HOST]
+
+    client = SaunumClient(host=host)
+
+    # Test connection
+    try:
+        await client.connect()
+    except SaunumConnectionError as exc:
+        raise ConfigEntryNotReady(f"Error connecting to {host}: {exc}") from exc
+
+    coordinator = LeilSaunaCoordinator(hass, client, entry)
+    await coordinator.async_config_entry_first_refresh()
+
+    entry.runtime_data = coordinator
+
+    await hass.config_entries.async_forward_entry_setups(entry, PLATFORMS)
+
+    return True
+
+
+async def async_unload_entry(hass: HomeAssistant, entry: LeilSaunaConfigEntry) -> bool:
+    """Unload a config entry."""
+    if unload_ok := await hass.config_entries.async_unload_platforms(entry, PLATFORMS):
+        coordinator = entry.runtime_data
+        coordinator.client.close()
+
+    return unload_ok

homeassistant/components/saunum/climate.py

@@ -0,0 +1,107 @@
+"""Climate platform for Saunum Leil Sauna Control Unit."""
+
+from __future__ import annotations
+
+import asyncio
+import logging
+from typing import Any
+
+from pysaunum import MAX_TEMPERATURE, MIN_TEMPERATURE, SaunumException
+
+from homeassistant.components.climate import (
+    ClimateEntity,
+    ClimateEntityFeature,
+    HVACAction,
+    HVACMode,
+)
+from homeassistant.const import ATTR_TEMPERATURE, UnitOfTemperature
+from homeassistant.core import HomeAssistant
+from homeassistant.exceptions import HomeAssistantError
+from homeassistant.helpers.entity_platform import AddConfigEntryEntitiesCallback
+
+from . import LeilSaunaConfigEntry
+from .const import DELAYED_REFRESH_SECONDS
+from .entity import LeilSaunaEntity
+
+_LOGGER = logging.getLogger(__name__)
+
+PARALLEL_UPDATES = 1
+
+
+async def async_setup_entry(
+    hass: HomeAssistant,
+    entry: LeilSaunaConfigEntry,
+    async_add_entities: AddConfigEntryEntitiesCallback,
+) -> None:
+    """Set up Saunum Leil Sauna climate entity."""
+    coordinator = entry.runtime_data
+    async_add_entities([LeilSaunaClimate(coordinator)])
+
+
+class LeilSaunaClimate(LeilSaunaEntity, ClimateEntity):
+    """Representation of a Saunum Leil Sauna climate entity."""
+
+    _attr_name = None
+    _attr_hvac_modes = [HVACMode.OFF, HVACMode.HEAT]
+    _attr_supported_features = ClimateEntityFeature.TARGET_TEMPERATURE
+    _attr_temperature_unit = UnitOfTemperature.CELSIUS
+    _attr_min_temp = MIN_TEMPERATURE
+    _attr_max_temp = MAX_TEMPERATURE
+
+    @property
+    def current_temperature(self) -> float | None:
+        """Return the current temperature in Celsius."""
+        return self.coordinator.data.current_temperature
+
+    @property
+    def target_temperature(self) -> float | None:
+        """Return the target temperature in Celsius."""
+        return self.coordinator.data.target_temperature
+
+    @property
+    def hvac_mode(self) -> HVACMode:
+        """Return current HVAC mode."""
+        session_active = self.coordinator.data.session_active
+        return HVACMode.HEAT if session_active else HVACMode.OFF
+
+    @property
+    def hvac_action(self) -> HVACAction | None:
+        """Return current HVAC action."""
+        if not self.coordinator.data.session_active:
+            return HVACAction.OFF
+
+        heater_elements_active = self.coordinator.data.heater_elements_active
+        return (
+            HVACAction.HEATING
+            if heater_elements_active and heater_elements_active > 0
+            else HVACAction.IDLE
+        )
+
+    async def async_set_hvac_mode(self, hvac_mode: HVACMode) -> None:
+        """Set new HVAC mode."""
+        try:
+            if hvac_mode == HVACMode.HEAT:
+                await self.coordinator.client.async_start_session()
+            else:
+                await self.coordinator.client.async_stop_session()
+        except SaunumException as err:
+            raise HomeAssistantError(f"Failed to set HVAC mode to {hvac_mode}") from err
+
+        # The device takes 1-2 seconds to turn heater elements on/off and
+        # update heater_elements_active. Wait and refresh again to ensure
+        # the HVAC action state reflects the actual heater status.
+        await asyncio.sleep(DELAYED_REFRESH_SECONDS.total_seconds())
+        await self.coordinator.async_request_refresh()
+
+    async def async_set_temperature(self, **kwargs: Any) -> None:
+        """Set new target temperature."""
+        try:
+            await self.coordinator.client.async_set_target_temperature(
+                int(kwargs[ATTR_TEMPERATURE])
+            )
+        except SaunumException as err:
+            raise HomeAssistantError(
+                f"Failed to set temperature to {kwargs[ATTR_TEMPERATURE]}"
+            ) from err
+
+        await self.coordinator.async_request_refresh()

homeassistant/components/saunum/config_flow.py

@@ -0,0 +1,76 @@
+"""Config flow for Saunum Leil Sauna Control Unit integration."""
+
+from __future__ import annotations
+
+import logging
+from typing import Any
+
+from pysaunum import SaunumClient, SaunumException
+import voluptuous as vol
+
+from homeassistant.config_entries import ConfigFlow, ConfigFlowResult
+from homeassistant.const import CONF_HOST
+from homeassistant.helpers import config_validation as cv
+
+from .const import DOMAIN
+
+_LOGGER = logging.getLogger(__name__)
+
+STEP_USER_DATA_SCHEMA = vol.Schema(
+    {
+        vol.Required(CONF_HOST): cv.string,
+    }
+)
+
+
+async def validate_input(data: dict[str, Any]) -> None:
+    """Validate the user input allows us to connect.
+
+    Data has the keys from STEP_USER_DATA_SCHEMA with values provided by the user.
+    """
+    host = data[CONF_HOST]
+
+    client = SaunumClient(host=host)
+
+    try:
+        await client.connect()
+        # Try to read data to verify communication
+        await client.async_get_data()
+    finally:
+        client.close()
+
+
+class LeilSaunaConfigFlow(ConfigFlow, domain=DOMAIN):
+    """Handle a config flow for Saunum Leil Sauna Control Unit."""
+
+    VERSION = 1
+    MINOR_VERSION = 1
+
+    async def async_step_user(
+        self, user_input: dict[str, Any] | None = None
+    ) -> ConfigFlowResult:
+        """Handle the initial step."""
+        errors: dict[str, str] = {}
+
+        if user_input is not None:
+            # Check for duplicate configuration
+            self._async_abort_entries_match(user_input)
+
+            try:
+                await validate_input(user_input)
+            except SaunumException:
+                errors["base"] = "cannot_connect"
+            except Exception:
+                _LOGGER.exception("Unexpected exception")
+                errors["base"] = "unknown"
+            else:
+                return self.async_create_entry(
+                    title="Saunum Leil Sauna",
+                    data=user_input,
+                )
+
+        return self.async_show_form(
+            step_id="user",
+            data_schema=STEP_USER_DATA_SCHEMA,
+            errors=errors,
+        )

homeassistant/components/saunum/const.py

@@ -0,0 +1,16 @@
+"""Constants for the Saunum Leil Sauna Control Unit integration."""
+
+from datetime import timedelta
+from typing import Final
+
+from homeassistant.const import Platform
+
+DOMAIN: Final = "saunum"
+
+# Platforms
+PLATFORMS: list[Platform] = [
+    Platform.CLIMATE,
+]
+
+DEFAULT_SCAN_INTERVAL: Final = timedelta(seconds=60)
+DELAYED_REFRESH_SECONDS: Final = timedelta(seconds=3)

homeassistant/components/saunum/coordinator.py

@@ -0,0 +1,47 @@
+"""Coordinator for Saunum Leil Sauna Control Unit integration."""
+
+from __future__ import annotations
+
+import logging
+from typing import TYPE_CHECKING
+
+from pysaunum import SaunumClient, SaunumData, SaunumException
+
+from homeassistant.core import HomeAssistant
+from homeassistant.helpers.update_coordinator import DataUpdateCoordinator, UpdateFailed
+
+from .const import DEFAULT_SCAN_INTERVAL, DOMAIN
+
+if TYPE_CHECKING:
+    from . import LeilSaunaConfigEntry
+
+_LOGGER = logging.getLogger(__name__)
+
+
+class LeilSaunaCoordinator(DataUpdateCoordinator[SaunumData]):
+    """Coordinator for fetching Saunum Leil Sauna data."""
+
+    config_entry: LeilSaunaConfigEntry
+
+    def __init__(
+        self,
+        hass: HomeAssistant,
+        client: SaunumClient,
+        config_entry: LeilSaunaConfigEntry,
+    ) -> None:
+        """Initialize the coordinator."""
+        super().__init__(
+            hass,
+            _LOGGER,
+            name=DOMAIN,
+            update_interval=DEFAULT_SCAN_INTERVAL,
+            config_entry=config_entry,
+        )
+        self.client = client
+
+    async def _async_update_data(self) -> SaunumData:
+        """Fetch data from the sauna controller."""
+        try:
+            return await self.client.async_get_data()
+        except SaunumException as err:
+            raise UpdateFailed(f"Communication error: {err}") from err

homeassistant/components/saunum/entity.py

@@ -0,0 +1,27 @@
+"""Base entity for Saunum Leil Sauna Control Unit integration."""
+
+from __future__ import annotations
+
+from homeassistant.helpers.device_registry import DeviceInfo
+from homeassistant.helpers.update_coordinator import CoordinatorEntity
+
+from .const import DOMAIN
+from .coordinator import LeilSaunaCoordinator
+
+
+class LeilSaunaEntity(CoordinatorEntity[LeilSaunaCoordinator]):
+    """Base entity for Saunum Leil Sauna."""
+
+    _attr_has_entity_name = True
+
+    def __init__(self, coordinator: LeilSaunaCoordinator) -> None:
+        """Initialize the entity."""
+        super().__init__(coordinator)
+        entry_id = coordinator.config_entry.entry_id
+        self._attr_unique_id = entry_id
+        self._attr_device_info = DeviceInfo(
+            identifiers={(DOMAIN, entry_id)},
+            name="Saunum Leil",
+            manufacturer="Saunum",
+            model="Leil Touch Panel",
+        )

homeassistant/components/saunum/manifest.json

@@ -0,0 +1,12 @@
+{
+  "domain": "saunum",
+  "name": "Saunum Leil",
+  "codeowners": ["@mettolen"],
+  "config_flow": true,
+  "documentation": "https://www.home-assistant.io/integrations/saunum",
+  "integration_type": "device",
+  "iot_class": "local_polling",
+  "loggers": ["pysaunum"],
+  "quality_scale": "silver",
+  "requirements": ["pysaunum==0.1.0"]
+}

homeassistant/components/saunum/quality_scale.yaml

@@ -0,0 +1,74 @@
+rules:
+  # Bronze
+  action-setup:
+    status: exempt
+    comment: Integration does not register custom actions.
+  appropriate-polling: done
+  brands: done
+  common-modules: done
+  config-flow-test-coverage: done
+  config-flow: done
+  dependency-transparency: done
+  docs-actions:
+    status: exempt
+    comment: Integration does not register custom actions.
+  docs-high-level-description: done
+  docs-installation-instructions: done
+  docs-removal-instructions: done
+  entity-event-setup:
+    status: exempt
+    comment: Integration does not explicitly subscribe to events.
+  entity-unique-id: done
+  has-entity-name: done
+  runtime-data: done
+  test-before-configure: done
+  test-before-setup: done
+  unique-config-entry: done
+
+  # Silver tier
+  action-exceptions: done
+  config-entry-unloading: done
+  docs-configuration-parameters: done
+  docs-installation-parameters: done
+  entity-unavailable: done
+  integration-owner: done
+  log-when-unavailable: done
+  parallel-updates: done
+  reauthentication-flow:
+    status: exempt
+    comment: Modbus TCP does not require authentication.
+  test-coverage: done
+
+  # Gold tier
+  devices: done
+  diagnostics: todo
+  discovery:
+    status: exempt
+    comment: Device uses generic Espressif hardware with no unique identifying information (MAC OUI or hostname) that would distinguish it from other Espressif-based devices on the network.
+  discovery-update-info: todo
+  docs-data-update: done
+  docs-examples: todo
+  docs-known-limitations: done
+  docs-supported-devices: todo
+  docs-supported-functions: done
+  docs-troubleshooting: done
+  docs-use-cases: done
+  dynamic-devices:
+    status: exempt
+    comment: Integration controls a single device; no dynamic device discovery needed.
+  entity-category: done
+  entity-device-class: done
+  entity-disabled-by-default: todo
+  entity-translations: todo
+  exception-translations: todo
+  icon-translations: todo
+  reconfiguration-flow: todo
+  repair-issues: todo
+  stale-devices:
+    status: exempt
+    comment: Integration controls a single device; no dynamic device discovery needed.
+
+  # Platinum
+  async-dependency: todo
+  inject-websession: todo
+  strict-typing: todo

homeassistant/components/saunum/strings.json

@@ -0,0 +1,22 @@
+{
+  "config": {
+    "abort": {
+      "already_configured": "[%key:common::config_flow::abort::already_configured_device%]"
+    },
+    "error": {
+      "cannot_connect": "[%key:common::config_flow::error::cannot_connect%]",
+      "unknown": "[%key:common::config_flow::error::unknown%]"
+    },
+    "step": {
+      "user": {
+        "data": {
+          "host": "[%key:common::config_flow::data::ip%]"
+        },
+        "data_description": {
+          "host": "IP address of your Saunum Leil sauna control unit"
+        },
+        "description": "To find the IP address, navigate to Settings → Modbus Settings on your Leil touch panel"
+      }
+    }
+  }
+}

homeassistant/generated/config_flows.py

@@ -575,6 +575,7 @@ FLOWS = {
         "samsungtv",
         "sanix",
         "satel_integra",
+        "saunum",
         "schlage",
         "scrape",
         "screenlogic",

homeassistant/generated/integrations.json

@@ -5757,6 +5757,12 @@
       "config_flow": true,
       "iot_class": "local_push"
     },
+    "saunum": {
+      "name": "Saunum Leil",
+      "integration_type": "device",
+      "config_flow": true,
+      "iot_class": "local_polling"
+    },
     "schlage": {
       "name": "Schlage",
       "integration_type": "hub",

requirements_all.txt

@@ -2339,6 +2339,9 @@ pysabnzbd==1.1.1
 # homeassistant.components.saj
 pysaj==0.0.16
 
+# homeassistant.components.saunum
+pysaunum==0.1.0
+
 # homeassistant.components.schlage
 pyschlage==2025.9.0
 

requirements_test_all.txt

@@ -1950,6 +1950,9 @@ pyrympro==0.0.9
 # homeassistant.components.sabnzbd
 pysabnzbd==1.1.1
 
+# homeassistant.components.saunum
+pysaunum==0.1.0
+
 # homeassistant.components.schlage
 pyschlage==2025.9.0
 

tests/components/saunum/__init__.py

@@ -0,0 +1 @@
+"""Tests for the Saunum integration."""

tests/components/saunum/conftest.py

@@ -0,0 +1,77 @@
+"""Configuration for Saunum Leil integration tests."""
+
+from collections.abc import Generator
+from unittest.mock import MagicMock, patch
+
+from pysaunum import SaunumData
+import pytest
+
+from homeassistant.components.saunum.const import DOMAIN
+from homeassistant.const import CONF_HOST
+from homeassistant.core import HomeAssistant
+
+from tests.common import MockConfigEntry
+
+
+@pytest.fixture
+def mock_config_entry() -> MockConfigEntry:
+    """Return the default mocked config entry."""
+    return MockConfigEntry(
+        entry_id="01K98T2T85R5GN0ZHYV25VFMMA",
+        title="Saunum Leil Sauna",
+        domain=DOMAIN,
+        data={CONF_HOST: "192.168.1.100"},
+    )
+
+
+@pytest.fixture
+def mock_saunum_client() -> Generator[MagicMock]:
+    """Return a mocked Saunum client for config flow and integration tests."""
+    with (
+        patch(
+            "homeassistant.components.saunum.config_flow.SaunumClient", autospec=True
+        ) as mock_client_class,
+        patch("homeassistant.components.saunum.SaunumClient", new=mock_client_class),
+    ):
+        mock_client = mock_client_class.return_value
+        mock_client.is_connected = True
+
+        # Create mock data for async_get_data
+        mock_data = SaunumData(
+            session_active=False,
+            sauna_type=0,
+            sauna_duration=120,
+            fan_duration=10,
+            target_temperature=80,
+            fan_speed=2,
+            light_on=False,
+            current_temperature=75.0,
+            on_time=3600,
+            heater_elements_active=0,
+            door_open=False,
+            alarm_door_open=False,
+            alarm_door_sensor=False,
+            alarm_thermal_cutoff=False,
+            alarm_internal_temp=False,
+            alarm_temp_sensor_short=False,
+            alarm_temp_sensor_open=False,
+        )
+
+        mock_client.async_get_data.return_value = mock_data
+
+        yield mock_client
+
+
+@pytest.fixture
+async def init_integration(
+    hass: HomeAssistant,
+    mock_config_entry: MockConfigEntry,
+    mock_saunum_client: MagicMock,
+) -> MockConfigEntry:
+    """Set up the integration for testing."""
+    mock_config_entry.add_to_hass(hass)
+
+    await hass.config_entries.async_setup(mock_config_entry.entry_id)
+    await hass.async_block_till_done()
+
+    return mock_config_entry

tests/components/saunum/snapshots/test_climate.ambr

@@ -0,0 +1,66 @@
+# serializer version: 1
+# name: test_entities[climate.saunum_leil-entry]
+  EntityRegistryEntrySnapshot({
+    'aliases': set({
+    }),
+    'area_id': None,
+    'capabilities': dict({
+      'hvac_modes': list([
+        <HVACMode.OFF: 'off'>,
+        <HVACMode.HEAT: 'heat'>,
+      ]),
+      'max_temp': 100,
+      'min_temp': 40,
+    }),
+    'config_entry_id': <ANY>,
+    'config_subentry_id': <ANY>,
+    'device_class': None,
+    'device_id': <ANY>,
+    'disabled_by': None,
+    'domain': 'climate',
+    'entity_category': None,
+    'entity_id': 'climate.saunum_leil',
+    'has_entity_name': True,
+    'hidden_by': None,
+    'icon': None,
+    'id': <ANY>,
+    'labels': set({
+    }),
+    'name': None,
+    'options': dict({
+    }),
+    'original_device_class': None,
+    'original_icon': None,
+    'original_name': None,
+    'platform': 'saunum',
+    'previous_unique_id': None,
+    'suggested_object_id': None,
+    'supported_features': <ClimateEntityFeature: 1>,
+    'translation_key': None,
+    'unique_id': '01K98T2T85R5GN0ZHYV25VFMMA',
+    'unit_of_measurement': None,
+  })
+# ---
+# name: test_entities[climate.saunum_leil-state]
+  StateSnapshot({
+    'attributes': ReadOnlyDict({
+      'current_temperature': 75.0,
+      'friendly_name': 'Saunum Leil',
+      'hvac_action': <HVACAction.OFF: 'off'>,
+      'hvac_modes': list([
+        <HVACMode.OFF: 'off'>,
+        <HVACMode.HEAT: 'heat'>,
+      ]),
+      'max_temp': 100,
+      'min_temp': 40,
+      'supported_features': <ClimateEntityFeature: 1>,
+      'temperature': 80,
+    }),
+    'context': <ANY>,
+    'entity_id': 'climate.saunum_leil',
+    'last_changed': <ANY>,
+    'last_reported': <ANY>,
+    'last_updated': <ANY>,
+    'state': 'off',
+  })
+# ---

tests/components/saunum/snapshots/test_init.ambr

@@ -0,0 +1,32 @@
+# serializer version: 1
+# name: test_device_entry
+  DeviceRegistryEntrySnapshot({
+    'area_id': None,
+    'config_entries': <ANY>,
+    'config_entries_subentries': <ANY>,
+    'configuration_url': None,
+    'connections': set({
+    }),
+    'disabled_by': None,
+    'entry_type': None,
+    'hw_version': None,
+    'id': <ANY>,
+    'identifiers': set({
+      tuple(
+        'saunum',
+        '01K98T2T85R5GN0ZHYV25VFMMA',
+      ),
+    }),
+    'labels': set({
+    }),
+    'manufacturer': 'Saunum',
+    'model': 'Leil Touch Panel',
+    'model_id': None,
+    'name': 'Saunum Leil',
+    'name_by_user': None,
+    'primary_config_entry': <ANY>,
+    'serial_number': None,
+    'sw_version': None,
+    'via_device_id': None,
+  })
+# ---

tests/components/saunum/test_climate.py

@@ -0,0 +1,232 @@
+"""Test the Saunum climate platform."""
+
+from __future__ import annotations
+
+from dataclasses import replace
+
+from freezegun.api import FrozenDateTimeFactory
+from pysaunum import SaunumException
+import pytest
+from syrupy.assertion import SnapshotAssertion
+
+from homeassistant.components.climate import (
+    ATTR_CURRENT_TEMPERATURE,
+    ATTR_HVAC_ACTION,
+    ATTR_HVAC_MODE,
+    DOMAIN as CLIMATE_DOMAIN,
+    SERVICE_SET_HVAC_MODE,
+    SERVICE_SET_TEMPERATURE,
+    HVACAction,
+    HVACMode,
+)
+from homeassistant.const import ATTR_ENTITY_ID, ATTR_TEMPERATURE, STATE_UNAVAILABLE
+from homeassistant.core import HomeAssistant
+from homeassistant.exceptions import HomeAssistantError
+from homeassistant.helpers import entity_registry as er
+
+from tests.common import MockConfigEntry, async_fire_time_changed, snapshot_platform
+
+
+@pytest.mark.usefixtures("entity_registry_enabled_by_default", "init_integration")
+async def test_entities(
+    hass: HomeAssistant,
+    snapshot: SnapshotAssertion,
+    mock_config_entry: MockConfigEntry,
+    entity_registry: er.EntityRegistry,
+) -> None:
+    """Test all entities."""
+    await snapshot_platform(hass, entity_registry, snapshot, mock_config_entry.entry_id)
+
+
+@pytest.mark.parametrize(
+    ("service", "service_data", "client_method", "expected_args"),
+    [
+        (
+            SERVICE_SET_HVAC_MODE,
+            {ATTR_HVAC_MODE: HVACMode.HEAT},
+            "async_start_session",
+            (),
+        ),
+        (
+            SERVICE_SET_HVAC_MODE,
+            {ATTR_HVAC_MODE: HVACMode.OFF},
+            "async_stop_session",
+            (),
+        ),
+        (
+            SERVICE_SET_TEMPERATURE,
+            {ATTR_TEMPERATURE: 85},
+            "async_set_target_temperature",
+            (85,),
+        ),
+    ],
+)
+@pytest.mark.usefixtures("init_integration")
+async def test_climate_service_calls(
+    hass: HomeAssistant,
+    mock_saunum_client,
+    service: str,
+    service_data: dict,
+    client_method: str,
+    expected_args: tuple,
+) -> None:
+    """Test climate service calls."""
+    entity_id = "climate.saunum_leil"
+
+    await hass.services.async_call(
+        CLIMATE_DOMAIN,
+        service,
+        {ATTR_ENTITY_ID: entity_id, **service_data},
+        blocking=True,
+    )
+
+    getattr(mock_saunum_client, client_method).assert_called_once_with(*expected_args)
+
+
+@pytest.mark.parametrize(
+    ("heater_elements_active", "expected_hvac_action"),
+    [
+        (3, HVACAction.HEATING),
+        (0, HVACAction.IDLE),
+    ],
+)
+async def test_climate_hvac_actions(
+    hass: HomeAssistant,
+    mock_config_entry: MockConfigEntry,
+    mock_saunum_client,
+    heater_elements_active: int,
+    expected_hvac_action: HVACAction,
+) -> None:
+    """Test climate HVAC actions when session is active."""
+    # Get the existing mock data and modify only what we need
+    mock_saunum_client.async_get_data.return_value.session_active = True
+    mock_saunum_client.async_get_data.return_value.heater_elements_active = (
+        heater_elements_active
+    )
+
+    mock_config_entry.add_to_hass(hass)
+
+    assert await hass.config_entries.async_setup(mock_config_entry.entry_id)
+    await hass.async_block_till_done()
+
+    entity_id = "climate.saunum_leil"
+    state = hass.states.get(entity_id)
+    assert state is not None
+
+    assert state.state == HVACMode.HEAT
+    assert state.attributes.get(ATTR_HVAC_ACTION) == expected_hvac_action
+
+
+@pytest.mark.parametrize(
+    (
+        "current_temperature",
+        "target_temperature",
+        "expected_current",
+        "expected_target",
+    ),
+    [
+        (None, 80, None, 80),
+        (35.0, 30, 35, 30),
+    ],
+)
+async def test_climate_temperature_edge_cases(
+    hass: HomeAssistant,
+    mock_config_entry: MockConfigEntry,
+    mock_saunum_client,
+    current_temperature: float | None,
+    target_temperature: int,
+    expected_current: float | None,
+    expected_target: int,
+) -> None:
+    """Test climate with edge case temperature values."""
+    # Get the existing mock data and modify only what we need
+    base_data = mock_saunum_client.async_get_data.return_value
+    mock_saunum_client.async_get_data.return_value = replace(
+        base_data,
+        current_temperature=current_temperature,
+        target_temperature=target_temperature,
+    )
+
+    mock_config_entry.add_to_hass(hass)
+
+    assert await hass.config_entries.async_setup(mock_config_entry.entry_id)
+    await hass.async_block_till_done()
+
+    entity_id = "climate.saunum_leil"
+    state = hass.states.get(entity_id)
+    assert state is not None
+
+    assert state.attributes.get(ATTR_CURRENT_TEMPERATURE) == expected_current
+    assert state.attributes.get(ATTR_TEMPERATURE) == expected_target
+
+
+@pytest.mark.usefixtures("init_integration")
+async def test_entity_unavailable_on_update_failure(
+    hass: HomeAssistant,
+    mock_saunum_client,
+    freezer: FrozenDateTimeFactory,
+) -> None:
+    """Test that entity becomes unavailable when coordinator update fails."""
+    entity_id = "climate.saunum_leil"
+
+    # Verify entity is initially available
+    state = hass.states.get(entity_id)
+    assert state is not None
+    assert state.state != STATE_UNAVAILABLE
+
+    # Make the next update fail
+    mock_saunum_client.async_get_data.side_effect = SaunumException("Read error")
+
+    # Move time forward to trigger a coordinator update (60 seconds)
+    freezer.tick(60)
+    async_fire_time_changed(hass)
+    await hass.async_block_till_done()
+
+    # Entity should now be unavailable
+    state = hass.states.get(entity_id)
+    assert state is not None
+    assert state.state == STATE_UNAVAILABLE
+
+
+@pytest.mark.parametrize(
+    ("service", "service_data", "client_method", "error_match"),
+    [
+        (
+            SERVICE_SET_HVAC_MODE,
+            {ATTR_HVAC_MODE: HVACMode.HEAT},
+            "async_start_session",
+            "Failed to set HVAC mode",
+        ),
+        (
+            SERVICE_SET_TEMPERATURE,
+            {ATTR_TEMPERATURE: 85},
+            "async_set_target_temperature",
+            "Failed to set temperature",
+        ),
+    ],
+)
+@pytest.mark.usefixtures("init_integration")
+async def test_action_error_handling(
+    hass: HomeAssistant,
+    mock_saunum_client,
+    service: str,
+    service_data: dict,
+    client_method: str,
+    error_match: str,
+) -> None:
+    """Test error handling when climate actions fail."""
+    entity_id = "climate.saunum_leil"
+
+    # Make the client method raise an exception
+    getattr(mock_saunum_client, client_method).side_effect = SaunumException(
+        "Communication error"
+    )
+
+    # Attempt to call service should raise HomeAssistantError
+    with pytest.raises(HomeAssistantError, match=error_match):
+        await hass.services.async_call(
+            CLIMATE_DOMAIN,
+            service,
+            {ATTR_ENTITY_ID: entity_id, **service_data},
+            blocking=True,
+        )

tests/components/saunum/test_config_flow.py

@@ -0,0 +1,98 @@
+"""Test the Saunum config flow."""
+
+from __future__ import annotations
+
+from pysaunum import SaunumConnectionError, SaunumException
+import pytest
+
+from homeassistant.components.saunum.const import DOMAIN
+from homeassistant.config_entries import SOURCE_USER
+from homeassistant.const import CONF_HOST
+from homeassistant.core import HomeAssistant
+from homeassistant.data_entry_flow import FlowResultType
+
+from tests.common import MockConfigEntry
+
+TEST_USER_INPUT = {CONF_HOST: "192.168.1.100"}
+
+
+@pytest.mark.usefixtures("mock_saunum_client")
+async def test_full_flow(hass: HomeAssistant) -> None:
+    """Test full flow."""
+    result = await hass.config_entries.flow.async_init(
+        DOMAIN, context={"source": SOURCE_USER}
+    )
+    assert result["type"] is FlowResultType.FORM
+    assert result["step_id"] == "user"
+    assert not result["errors"]
+
+    result = await hass.config_entries.flow.async_configure(
+        result["flow_id"],
+        TEST_USER_INPUT,
+    )
+
+    assert result["type"] is FlowResultType.CREATE_ENTRY
+    assert result["title"] == "Saunum Leil Sauna"
+    assert result["data"] == TEST_USER_INPUT
+
+
+@pytest.mark.parametrize(
+    ("side_effect", "error_base"),
+    [
+        (SaunumConnectionError("Connection failed"), "cannot_connect"),
+        (SaunumException("Read error"), "cannot_connect"),
+        (Exception("Unexpected error"), "unknown"),
+    ],
+)
+async def test_form_errors(
+    hass: HomeAssistant,
+    mock_saunum_client,
+    side_effect: Exception,
+    error_base: str,
+) -> None:
+    """Test error handling and recovery."""
+    mock_saunum_client.connect.side_effect = side_effect
+
+    result = await hass.config_entries.flow.async_init(
+        DOMAIN, context={"source": SOURCE_USER}
+    )
+
+    result = await hass.config_entries.flow.async_configure(
+        result["flow_id"],
+        TEST_USER_INPUT,
+    )
+
+    assert result["type"] is FlowResultType.FORM
+    assert result["errors"] == {"base": error_base}
+
+    # Test recovery - clear the error and try again
+    mock_saunum_client.connect.side_effect = None
+
+    result = await hass.config_entries.flow.async_configure(
+        result["flow_id"],
+        TEST_USER_INPUT,
+    )
+
+    assert result["type"] is FlowResultType.CREATE_ENTRY
+    assert result["title"] == "Saunum Leil Sauna"
+    assert result["data"] == TEST_USER_INPUT
+
+
+@pytest.mark.usefixtures("mock_saunum_client")
+async def test_form_duplicate(
+    hass: HomeAssistant, mock_config_entry: MockConfigEntry
+) -> None:
+    """Test duplicate entry handling."""
+    mock_config_entry.add_to_hass(hass)
+
+    result = await hass.config_entries.flow.async_init(
+        DOMAIN, context={"source": SOURCE_USER}
+    )
+
+    result = await hass.config_entries.flow.async_configure(
+        result["flow_id"],
+        TEST_USER_INPUT,
+    )
+
+    assert result["type"] is FlowResultType.ABORT
+    assert result["reason"] == "already_configured"

tests/components/saunum/test_init.py

@@ -0,0 +1,56 @@
+"""Test Saunum Leil integration setup and teardown."""
+
+from pysaunum import SaunumConnectionError
+import pytest
+from syrupy.assertion import SnapshotAssertion
+
+from homeassistant.components.saunum.const import DOMAIN
+from homeassistant.config_entries import ConfigEntryState
+from homeassistant.core import HomeAssistant
+from homeassistant.helpers import device_registry as dr
+
+from tests.common import MockConfigEntry
+
+
+async def test_setup_and_unload(
+    hass: HomeAssistant,
+    mock_config_entry: MockConfigEntry,
+    mock_saunum_client,
+) -> None:
+    """Test integration setup and unload."""
+    mock_config_entry.add_to_hass(hass)
+
+    assert await hass.config_entries.async_setup(mock_config_entry.entry_id)
+    assert mock_config_entry.state is ConfigEntryState.LOADED
+
+    assert await hass.config_entries.async_unload(mock_config_entry.entry_id)
+    assert mock_config_entry.state is ConfigEntryState.NOT_LOADED
+
+
+async def test_async_setup_entry_connection_failed(
+    hass: HomeAssistant,
+    mock_config_entry: MockConfigEntry,
+    mock_saunum_client,
+) -> None:
+    """Test integration setup fails when connection cannot be established."""
+    mock_config_entry.add_to_hass(hass)
+
+    mock_saunum_client.connect.side_effect = SaunumConnectionError("Connection failed")
+
+    assert not await hass.config_entries.async_setup(mock_config_entry.entry_id)
+
+    assert mock_config_entry.state is ConfigEntryState.SETUP_RETRY
+
+
+@pytest.mark.usefixtures("init_integration")
+async def test_device_entry(
+    device_registry: dr.DeviceRegistry,
+    snapshot: SnapshotAssertion,
+) -> None:
+    """Test device registry entry."""
+    assert (
+        device_entry := device_registry.async_get_device(
+            identifiers={(DOMAIN, "01K98T2T85R5GN0ZHYV25VFMMA")}
+        )
+    )
+    assert device_entry == snapshot