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_health.py

@@ -0,0 +1,122 @@
+"""
+Unit tests for handler_base.health module.
+"""
+import pytest
+import json
+import threading
+import time
+from http.client import HTTPConnection
+from unittest.mock import AsyncMock
+
+
+class TestHealthServer:
+    """Tests for HealthServer."""
+    
+    @pytest.fixture
+    def health_server(self, settings):
+        """Create a HealthServer instance."""
+        from handler_base.health import HealthServer
+        
+        # Use a random high port to avoid conflicts
+        settings.health_port = 18080
+        return HealthServer(settings)
+    
+    def test_start_stop(self, health_server):
+        """Test starting and stopping the health server."""
+        health_server.start()
+        time.sleep(0.1)  # Give server time to start
+        
+        # Verify server is running
+        assert health_server._server is not None
+        assert health_server._thread is not None
+        assert health_server._thread.is_alive()
+        
+        health_server.stop()
+        time.sleep(0.1)
+        
+        assert health_server._server is None
+    
+    def test_health_endpoint(self, health_server):
+        """Test the /health endpoint."""
+        health_server.start()
+        time.sleep(0.1)
+        
+        try:
+            conn = HTTPConnection("localhost", 18080, timeout=5)
+            conn.request("GET", "/health")
+            response = conn.getresponse()
+            
+            assert response.status == 200
+            data = json.loads(response.read().decode())
+            assert data["status"] == "healthy"
+        finally:
+            conn.close()
+            health_server.stop()
+    
+    def test_ready_endpoint_default(self, health_server):
+        """Test the /ready endpoint with no custom check."""
+        health_server.start()
+        time.sleep(0.1)
+        
+        try:
+            conn = HTTPConnection("localhost", 18080, timeout=5)
+            conn.request("GET", "/ready")
+            response = conn.getresponse()
+            
+            assert response.status == 200
+            data = json.loads(response.read().decode())
+            assert data["status"] == "ready"
+        finally:
+            conn.close()
+            health_server.stop()
+    
+    def test_ready_endpoint_with_check(self, settings):
+        """Test /ready endpoint with custom readiness check."""
+        from handler_base.health import HealthServer
+        
+        ready_flag = [False]  # Use list to allow mutation in closure
+        
+        async def check_ready():
+            return ready_flag[0]
+        
+        settings.health_port = 18081
+        server = HealthServer(settings, ready_check=check_ready)
+        server.start()
+        time.sleep(0.2)
+        
+        try:
+            conn = HTTPConnection("localhost", 18081, timeout=5)
+            
+            # Should be not ready initially
+            conn.request("GET", "/ready")
+            response = conn.getresponse()
+            response.read()  # Consume response body
+            assert response.status == 503
+            
+            # Mark as ready
+            ready_flag[0] = True
+            
+            # Need new connection after consuming response
+            conn.close()
+            conn = HTTPConnection("localhost", 18081, timeout=5)
+            conn.request("GET", "/ready")
+            response = conn.getresponse()
+            assert response.status == 200
+        finally:
+            conn.close()
+            server.stop()
+    
+    def test_404_for_unknown_path(self, health_server):
+        """Test that unknown paths return 404."""
+        health_server.start()
+        time.sleep(0.1)
+        
+        try:
+            conn = HTTPConnection("localhost", 18080, timeout=5)
+            conn.request("GET", "/unknown")
+            response = conn.getresponse()
+            
+            assert response.status == 404
+        finally:
+            conn.close()
+            health_server.stop()