diff --git a/tests/components/fluss/test_config_flow.py b/tests/components/fluss/test_config_flow.py
index 8d44c3eeac5..fe686ddcd09 100644
--- a/tests/components/fluss/test_config_flow.py
+++ b/tests/components/fluss/test_config_flow.py
@@ -1,4 +1,4 @@
-"""Tests for the Fluss integration's config flow."""
+"""Tests for the Fluss+ integration's config flow."""
 
 from unittest.mock import patch
 
@@ -7,75 +7,106 @@ from fluss_api import (
     FlussApiClientCommunicationError,
 )
 import pytest
+import voluptuous as vol
 
-from homeassistant.components.fluss.config_flow import FlussConfigFlow
+from homeassistant.components.fluss.config_flow import (
+    STEP_USER_DATA_SCHEMA,
+    FlussConfigFlow,
+)
+from homeassistant.const import CONF_API_KEY
+from homeassistant.data_entry_flow import FlowResultType
 
 
 @pytest.fixture
-def config_flow():
-    """Fixture to create a FlussConfigFlow instance."""
-    return FlussConfigFlow()
+def config_flow(hass):
+    """Fixture to create a FlussConfigFlow instance with hass."""
+    flow = FlussConfigFlow()
+    flow.hass = hass
+    return flow
+
+
+async def test_step_user_initial_form(config_flow: FlussConfigFlow) -> None:
+    """Test initial form display when no user input is provided."""
+    result = await config_flow.async_step_user(user_input=None)
+
+    assert result["type"] == FlowResultType.FORM
+    assert result["step_id"] == "user"
+    assert result["data_schema"] == STEP_USER_DATA_SCHEMA
+    assert result["errors"] == {}
 
 
 async def test_step_user_success(config_flow: FlussConfigFlow) -> None:
     """Test successful user step."""
-    user_input = {"api_key": "valid_api_key"}
-
-    with patch(
-        "homeassistant.components.fluss.config_flow.FlussApiClient"
-    ) as mock_client:
-        mock_client.return_value = None  # Simulate successful client creation
+    user_input = {CONF_API_KEY: "valid_api_key"}
 
+    with patch("homeassistant.components.fluss.config_flow.FlussApiClient") as mock_client:
+        mock_client.return_value = None
         result = await config_flow.async_step_user(user_input)
 
-    assert result["type"] == "create_entry"
-    assert result["title"] == "Fluss Device"
+    assert result["type"] == FlowResultType.CREATE_ENTRY
+    assert result["title"] == "My Fluss+ Devices"
     assert result["data"] == user_input
 
 
 async def test_step_user_invalid_auth(config_flow: FlussConfigFlow) -> None:
     """Test invalid authentication."""
-    user_input = {"api_key": "invalid_api_key"}
-    with patch(
-        "homeassistant.components.fluss.config_flow.FlussApiClient"
-    ) as mock_client:
-        mock_client.side_effect = (
-            FlussApiClientAuthenticationError  # Simulate invalid authentication
-        )
+    user_input = {CONF_API_KEY: "invalid_api_key"}
+
+    with patch("homeassistant.components.fluss.config_flow.FlussApiClient") as mock_client:
+        mock_client.side_effect = FlussApiClientAuthenticationError
         result = await config_flow.async_step_user(user_input)
 
-    assert result["type"] == "form"
+    assert result["type"] == FlowResultType.FORM
+    assert result["step_id"] == "user"
     assert result["errors"] == {"base": "invalid_auth"}
 
 
-@pytest.mark.asyncio
 async def test_step_user_cannot_connect(config_flow: FlussConfigFlow) -> None:
     """Test connection failure."""
-    user_input = {"api_key": "some_api_key"}
-    with patch(
-        "homeassistant.components.fluss.config_flow.FlussApiClient"
-    ) as mock_client:
-        mock_client.side_effect = (
-            FlussApiClientCommunicationError  # Simulate communication error
-        )
+    user_input = {CONF_API_KEY: "some_api_key"}
+
+    with patch("homeassistant.components.fluss.config_flow.FlussApiClient") as mock_client:
+        mock_client.side_effect = FlussApiClientCommunicationError
         result = await config_flow.async_step_user(user_input)
 
-    assert result["type"] == "form"
+    assert result["type"] == FlowResultType.FORM
+    assert result["step_id"] == "user"
     assert result["errors"] == {"base": "cannot_connect"}
 
 
-async def test_step_user_unexpected_error(config_flow) -> None:
-    """Test unexpected exception handling."""
-    user_input = {"api_key": "some_api_key"}
+async def test_step_user_unexpected_error(config_flow: FlussConfigFlow, caplog) -> None:
+    """Test unexpected exception handling with logging."""
+    user_input = {CONF_API_KEY: "some_api_key"}
 
-    with patch(
-        "homeassistant.components.fluss.config_flow.FlussApiClient"
-    ) as mock_client:
-        mock_client.side_effect = Exception(
-            "Unexpected error"
-        )  # Simulate unexpected error
+    with patch("homeassistant.components.fluss.config_flow.FlussApiClient") as mock_client:
+        mock_client.side_effect = Exception("Unexpected error")
+        with caplog.at_level("ERROR"):
+            result = await config_flow.async_step_user(user_input)
 
-        result = await config_flow.async_step_user(user_input)
-
-    assert result["type"] == "form"
+    assert result["type"] == FlowResultType.FORM
+    assert result["step_id"] == "user"
     assert result["errors"] == {"base": "unknown"}
+    assert "Unexpected exception occurred" in caplog.text
+
+
+async def test_single_instance_allowed(config_flow: FlussConfigFlow) -> None:
+    """Test that only one instance is allowed."""
+    with patch.object(config_flow, "_async_current_entries", return_value=[True]):
+        result = await config_flow.async_step_user(None)
+
+    assert result["type"] == FlowResultType.ABORT
+    assert result["reason"] == "single_instance_allowed"
+
+
+def test_data_schema_validation():
+    """Test that the data schema enforces required string field."""
+    # Valid input
+    STEP_USER_DATA_SCHEMA({CONF_API_KEY: "test_key"})
+
+    # Missing key
+    with pytest.raises(vol.error.MultipleInvalid):
+        STEP_USER_DATA_SCHEMA({})
+
+    # Non-string value
+    with pytest.raises(vol.error.MultipleInvalid):
+        STEP_USER_DATA_SCHEMA({CONF_API_KEY: 123})