Fix Hanna sensors showing readings from another device (#184258)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

homeassistant/components/hanna/coordinator.py

@@ -50,7 +50,7 @@ class HannaDataCoordinator(DataUpdateCoordinator[dict[str, Any]]):
 
     def get_parameters(self) -> list[dict[str, Any]]:
         """Get all parameters from the sensor data."""
-        return self.api_client.parameters
+        return self.data.get("messages", {}).get("parameters", [])
 
     def get_parameter_value(self, key: str) -> Any:
         """Get the value for a specific parameter."""

tests/components/hanna/test_sensor.py

@@ -0,0 +1,47 @@
+"""Tests for the Hanna Instruments sensor platform."""
+
+from typing import Any
+from unittest.mock import MagicMock
+
+from homeassistant.const import Platform
+from homeassistant.core import HomeAssistant
+from homeassistant.helpers import entity_registry as er
+
+from tests.common import MockConfigEntry
+
+DEVICE_READINGS = {
+    "pool": {"DID": "pool", "messages": {"parameters": [{"name": "ph", "value": 7.2}]}},
+    "spa": {"DID": "spa", "messages": {"parameters": [{"name": "ph", "value": 7.8}]}},
+}
+
+
+async def test_sensors_use_own_device_readings(
+    hass: HomeAssistant,
+    entity_registry: er.EntityRegistry,
+    mock_hanna_client: MagicMock,
+    mock_config_entry: MockConfigEntry,
+) -> None:
+    """Test each device's sensors show that device's readings."""
+    mock_hanna_client.get_devices.return_value = [
+        {"DID": "pool", "name": "Pool"},
+        {"DID": "spa", "name": "Spa"},
+    ]
+
+    def get_last_device_reading(device_id: str) -> dict[str, Any]:
+        # The real client keeps only the most recently fetched device's parameters.
+        readings = DEVICE_READINGS[device_id]
+        mock_hanna_client.parameters = readings["messages"]["parameters"]
+        return readings
+
+    mock_hanna_client.get_last_device_reading.side_effect = get_last_device_reading
+
+    mock_config_entry.add_to_hass(hass)
+    await hass.config_entries.async_setup(mock_config_entry.entry_id)
+    await hass.async_block_till_done()
+
+    pool_ph = entity_registry.async_get_entity_id(Platform.SENSOR, "hanna", "pool_ph")
+    spa_ph = entity_registry.async_get_entity_id(Platform.SENSOR, "hanna", "spa_ph")
+    assert pool_ph is not None
+    assert spa_ph is not None
+    assert hass.states.get(pool_ph).state == "7.2"
+    assert hass.states.get(spa_ph).state == "7.8"