test: add unit tests for handler-base

- tests/conftest.py: Pytest fixtures and configuration
- tests/unit/test_config.py: Settings tests
- tests/unit/test_nats_client.py: NATS client tests
- tests/unit/test_health.py: Health server tests
- tests/unit/test_clients.py: Service client tests
- pytest.ini: Pytest configuration

tests/unit/test_clients.py

@@ -0,0 +1,156 @@
+"""
+Unit tests for service clients.
+"""
+import json
+import pytest
+from unittest.mock import AsyncMock, MagicMock, patch
+
+
+class TestEmbeddingsClient:
+    """Tests for EmbeddingsClient."""
+    
+    @pytest.fixture
+    def embeddings_client(self, mock_httpx_client):
+        """Create an EmbeddingsClient with mocked HTTP."""
+        from handler_base.clients.embeddings import EmbeddingsClient
+        
+        client = EmbeddingsClient()
+        client._client = mock_httpx_client
+        return client
+    
+    @pytest.mark.asyncio
+    async def test_embed_single(self, embeddings_client, mock_httpx_client, sample_embedding):
+        """Test embedding a single text."""
+        # Setup mock response
+        mock_response = MagicMock()
+        mock_response.json.return_value = {
+            "data": [{"embedding": sample_embedding, "index": 0}]
+        }
+        mock_response.raise_for_status = MagicMock()
+        mock_httpx_client.post.return_value = mock_response
+        
+        result = await embeddings_client.embed_single("Hello world")
+        
+        assert result == sample_embedding
+        mock_httpx_client.post.assert_called_once()
+    
+    @pytest.mark.asyncio
+    async def test_embed_batch(self, embeddings_client, mock_httpx_client, sample_embedding):
+        """Test embedding multiple texts."""
+        texts = ["Hello", "World"]
+        
+        mock_response = MagicMock()
+        mock_response.json.return_value = {
+            "data": [
+                {"embedding": sample_embedding, "index": 0},
+                {"embedding": sample_embedding, "index": 1},
+            ]
+        }
+        mock_response.raise_for_status = MagicMock()
+        mock_httpx_client.post.return_value = mock_response
+        
+        result = await embeddings_client.embed(texts)
+        
+        assert len(result) == 2
+        assert all(len(e) == len(sample_embedding) for e in result)
+    
+    @pytest.mark.asyncio
+    async def test_health_check(self, embeddings_client, mock_httpx_client):
+        """Test health check."""
+        mock_response = MagicMock()
+        mock_response.status_code = 200
+        mock_httpx_client.get.return_value = mock_response
+        
+        result = await embeddings_client.health()
+        
+        assert result is True
+
+
+class TestRerankerClient:
+    """Tests for RerankerClient."""
+    
+    @pytest.fixture
+    def reranker_client(self, mock_httpx_client):
+        """Create a RerankerClient with mocked HTTP."""
+        from handler_base.clients.reranker import RerankerClient
+        
+        client = RerankerClient()
+        client._client = mock_httpx_client
+        return client
+    
+    @pytest.mark.asyncio
+    async def test_rerank(self, reranker_client, mock_httpx_client, sample_documents):
+        """Test reranking documents."""
+        texts = [d["text"] for d in sample_documents]
+        
+        mock_response = MagicMock()
+        mock_response.json.return_value = {
+            "results": [
+                {"index": 1, "relevance_score": 0.95},
+                {"index": 0, "relevance_score": 0.80},
+                {"index": 2, "relevance_score": 0.65},
+            ]
+        }
+        mock_response.raise_for_status = MagicMock()
+        mock_httpx_client.post.return_value = mock_response
+        
+        result = await reranker_client.rerank("What is ML?", texts)
+        
+        assert len(result) == 3
+        assert result[0]["score"] == 0.95
+        assert result[0]["index"] == 1
+
+
+class TestLLMClient:
+    """Tests for LLMClient."""
+    
+    @pytest.fixture
+    def llm_client(self, mock_httpx_client):
+        """Create an LLMClient with mocked HTTP."""
+        from handler_base.clients.llm import LLMClient
+        
+        client = LLMClient()
+        client._client = mock_httpx_client
+        return client
+    
+    @pytest.mark.asyncio
+    async def test_generate(self, llm_client, mock_httpx_client):
+        """Test generating a response."""
+        mock_response = MagicMock()
+        mock_response.json.return_value = {
+            "choices": [
+                {"message": {"content": "Hello! I'm an AI assistant."}}
+            ],
+            "usage": {"prompt_tokens": 10, "completion_tokens": 20}
+        }
+        mock_response.raise_for_status = MagicMock()
+        mock_httpx_client.post.return_value = mock_response
+        
+        result = await llm_client.generate("Hello")
+        
+        assert result == "Hello! I'm an AI assistant."
+    
+    @pytest.mark.asyncio
+    async def test_generate_with_context(self, llm_client, mock_httpx_client):
+        """Test generating with RAG context."""
+        mock_response = MagicMock()
+        mock_response.json.return_value = {
+            "choices": [
+                {"message": {"content": "Based on the context..."}}
+            ],
+            "usage": {}
+        }
+        mock_response.raise_for_status = MagicMock()
+        mock_httpx_client.post.return_value = mock_response
+        
+        result = await llm_client.generate(
+            "What is Python?",
+            context="Python is a programming language."
+        )
+        
+        assert "Based on the context" in result
+        
+        # Verify context was included in the request
+        call_args = mock_httpx_client.post.call_args
+        messages = call_args.kwargs["json"]["messages"]
+        assert any("Context:" in m["content"] for m in messages if m["role"] == "user")