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_nats_client.py

@@ -0,0 +1,91 @@
+"""
+Unit tests for handler_base.nats_client module.
+"""
+import pytest
+from unittest.mock import AsyncMock, MagicMock, patch
+import msgpack
+
+
+class TestNATSClient:
+    """Tests for NATSClient."""
+    
+    @pytest.fixture
+    def nats_client(self, settings):
+        """Create a NATSClient instance."""
+        from handler_base.nats_client import NATSClient
+        return NATSClient(settings)
+    
+    def test_init(self, nats_client, settings):
+        """Test NATSClient initialization."""
+        assert nats_client.settings == settings
+        assert nats_client._nc is None
+        assert nats_client._js is None
+    
+    def test_decode_msgpack(self, nats_client):
+        """Test msgpack decoding."""
+        data = {"query": "hello", "request_id": "123"}
+        encoded = msgpack.packb(data, use_bin_type=True)
+        
+        msg = MagicMock()
+        msg.data = encoded
+        
+        result = nats_client.decode_msgpack(msg)
+        assert result == data
+    
+    def test_decode_json(self, nats_client):
+        """Test JSON decoding."""
+        import json
+        data = {"query": "hello"}
+        
+        msg = MagicMock()
+        msg.data = json.dumps(data).encode()
+        
+        result = nats_client.decode_json(msg)
+        assert result == data
+    
+    @pytest.mark.asyncio
+    async def test_connect(self, nats_client):
+        """Test NATS connection."""
+        with patch("handler_base.nats_client.nats") as mock_nats:
+            mock_nc = AsyncMock()
+            mock_js = MagicMock()
+            mock_nc.jetstream = MagicMock(return_value=mock_js)  # Not async
+            mock_nats.connect = AsyncMock(return_value=mock_nc)
+            
+            await nats_client.connect()
+            
+            assert nats_client._nc == mock_nc
+            assert nats_client._js == mock_js
+            mock_nats.connect.assert_called_once()
+    
+    @pytest.mark.asyncio
+    async def test_publish(self, nats_client):
+        """Test publishing a message."""
+        mock_nc = AsyncMock()
+        nats_client._nc = mock_nc
+        
+        data = {"key": "value"}
+        await nats_client.publish("test.subject", data)
+        
+        mock_nc.publish.assert_called_once()
+        call_args = mock_nc.publish.call_args
+        assert call_args.args[0] == "test.subject"
+        
+        # Verify msgpack encoding
+        decoded = msgpack.unpackb(call_args.args[1], raw=False)
+        assert decoded == data
+    
+    @pytest.mark.asyncio
+    async def test_subscribe(self, nats_client):
+        """Test subscribing to a subject."""
+        mock_nc = AsyncMock()
+        mock_sub = MagicMock()
+        mock_nc.subscribe = AsyncMock(return_value=mock_sub)
+        nats_client._nc = mock_nc
+        
+        handler = AsyncMock()
+        await nats_client.subscribe("test.subject", handler, queue="test-queue")
+        
+        mock_nc.subscribe.assert_called_once()
+        call_kwargs = mock_nc.subscribe.call_args.kwargs
+        assert call_kwargs["queue"] == "test-queue"