Warn user if Gateway is already paired (#57530)

* Warn user if Gateway is already paired.

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

homeassistant/components/tradfri/config_flow.py

@@ -182,7 +182,8 @@ async def authenticate(
         raise AuthError("timeout") from err
     finally:
         await api_factory.shutdown()
-
+    if key is None:
+        raise AuthError("cannot_authenticate")
     return await get_gateway_info(hass, host, identity, key)
 
 

homeassistant/components/tradfri/strings.json

@@ -13,7 +13,8 @@
     "error": {
       "invalid_key": "Failed to register with provided key. If this keeps happening, try restarting the gateway.",
       "cannot_connect": "[%key:common::config_flow::error::cannot_connect%]",
-      "timeout": "Timeout validating the code."
+      "timeout": "Timeout validating the code.",
+      "cannot_authenticate": "Cannot authenticate, is Gateway paired with another server like e.g. Homekit?"
     },
     "abort": {
       "already_configured": "[%key:common::config_flow::abort::already_configured_device%]",

tests/components/tradfri/test_config_flow.py

@@ -1,5 +1,5 @@
 """Test the Tradfri config flow."""
-from unittest.mock import patch
+from unittest.mock import AsyncMock, patch
 
 import pytest
 
@@ -18,6 +18,26 @@ def mock_auth():
         yield mock_auth
 
 
+async def test_already_paired(hass, mock_entry_setup):
+    """Test Gateway already paired."""
+    with patch(
+        "homeassistant.components.tradfri.config_flow.APIFactory",
+        autospec=True,
+    ) as mock_lib:
+        mx = AsyncMock()
+        mx.generate_psk.return_value = None
+        mock_lib.init.return_value = mx
+        result = await hass.config_entries.flow.async_init(
+            "tradfri", context={"source": config_entries.SOURCE_USER}
+        )
+        result = await hass.config_entries.flow.async_configure(
+            result["flow_id"], {"host": "123.123.123.123", "security_code": "abcd"}
+        )
+
+    assert result["type"] == data_entry_flow.RESULT_TYPE_FORM
+    assert result["errors"] == {"base": "cannot_authenticate"}
+
+
 async def test_user_connection_successful(hass, mock_auth, mock_entry_setup):
     """Test a successful connection."""
     mock_auth.side_effect = lambda hass, host, code: {"host": host, "gateway_id": "bla"}