Update vLLM health check to use /health endpoint

- Replace models.list() call with HTTP GET to /health endpoint
- Remove API token validation since /health is unauthenticated
- Use urllib.parse.urljoin for cleaner URL construction
- Update tests to mock httpx.AsyncClient instead of OpenAI client
- Health check now works regardless of API token configuration

Signed-off-by: Akram Ben Aissi <akram.benaissi@gmail.com>

tests/unit/providers/inference/test_remote_vllm.py

@@ -563,34 +563,29 @@ async def test_health_status_success(vllm_inference_adapter):
     """
     Test the health method of VLLM InferenceAdapter when the connection is successful.
 
-    This test verifies that the health method returns a HealthResponse with status OK, only
-    when the connection to the vLLM server is successful.
+    This test verifies that the health method returns a HealthResponse with status OK
+    when the /health endpoint responds successfully.
     """
-    # Set a non-default API token to enable health check
-    vllm_inference_adapter.config.api_token = "real-api-key"
+    with patch("httpx.AsyncClient") as mock_client_class:
+        # Create mock response
+        mock_response = MagicMock()
+        mock_response.raise_for_status.return_value = None
 
-    with patch.object(VLLMInferenceAdapter, "client", new_callable=PropertyMock) as mock_create_client:
-        # Create mock client and models
-        mock_client = MagicMock()
-        mock_models = MagicMock()
-
-        # Create a mock async iterator that yields a model when iterated
-        async def mock_list():
-            for model in [MagicMock()]:
-                yield model
-
-        # Set up the models.list to return our mock async iterator
-        mock_models.list.return_value = mock_list()
-        mock_client.models = mock_models
-        mock_create_client.return_value = mock_client
+        # Create mock client instance
+        mock_client_instance = MagicMock()
+        mock_client_instance.get.return_value = mock_response
+        mock_client_class.return_value.__aenter__.return_value = mock_client_instance
 
         # Call the health method
         health_response = await vllm_inference_adapter.health()
+
         # Verify the response
         assert health_response["status"] == HealthStatus.OK
 
-        # Verify that models.list was called
-        mock_models.list.assert_called_once()
+        # Verify that the health endpoint was called
+        mock_client_instance.get.assert_called_once()
+        call_args = mock_client_instance.get.call_args[0]
+        assert call_args[0].endswith("/health")
 
 
 async def test_health_status_failure(vllm_inference_adapter):
@@ -600,48 +595,42 @@ async def test_health_status_failure(vllm_inference_adapter):
     This test verifies that the health method returns a HealthResponse with status ERROR
     and an appropriate error message when the connection to the vLLM server fails.
     """
-    # Set a non-default API token to enable health check
-    vllm_inference_adapter.config.api_token = "real-api-key"
-
-    with patch.object(VLLMInferenceAdapter, "client", new_callable=PropertyMock) as mock_create_client:
-        # Create mock client and models
-        mock_client = MagicMock()
-        mock_models = MagicMock()
-
-        # Create a mock async iterator that raises an exception when iterated
-        async def mock_list():
-            raise Exception("Connection failed")
-            yield  # Unreachable code
-
-        # Set up the models.list to return our mock async iterator
-        mock_models.list.return_value = mock_list()
-        mock_client.models = mock_models
-        mock_create_client.return_value = mock_client
+    with patch("httpx.AsyncClient") as mock_client_class:
+        # Create mock client instance that raises an exception
+        mock_client_instance = MagicMock()
+        mock_client_instance.get.side_effect = Exception("Connection failed")
+        mock_client_class.return_value.__aenter__.return_value = mock_client_instance
 
         # Call the health method
         health_response = await vllm_inference_adapter.health()
+
         # Verify the response
         assert health_response["status"] == HealthStatus.ERROR
         assert "Health check failed: Connection failed" in health_response["message"]
 
-        mock_models.list.assert_called_once()
-
 
 async def test_health_status_no_static_api_key(vllm_inference_adapter):
     """
     Test the health method of VLLM InferenceAdapter when no static API key is provided.
 
     This test verifies that the health method returns a HealthResponse with status OK
-    without performing any connectivity test when no static API key is provided.
+    when the /health endpoint responds successfully, regardless of API token configuration.
     """
-    # Ensure api_token is the default value (no static API key)
-    vllm_inference_adapter.config.api_token = "fake"
+    with patch("httpx.AsyncClient") as mock_client_class:
+        # Create mock response
+        mock_response = MagicMock()
+        mock_response.raise_for_status.return_value = None
 
-    # Call the health method
-    health_response = await vllm_inference_adapter.health()
+        # Create mock client instance
+        mock_client_instance = MagicMock()
+        mock_client_instance.get.return_value = mock_response
+        mock_client_class.return_value.__aenter__.return_value = mock_client_instance
 
-    # Verify the response
-    assert health_response["status"] == HealthStatus.OK
+        # Call the health method
+        health_response = await vllm_inference_adapter.health()
+
+        # Verify the response
+        assert health_response["status"] == HealthStatus.OK
 
 
 async def test_openai_chat_completion_is_async(vllm_inference_adapter):