test: add unit tests for HealthCheckServer

tests/om1_utils/healthcheck/test_healthcheck.py

@@ -0,0 +1,79 @@
+import socket
+import time
+from contextlib import closing
+
+import pytest
+import requests
+
+from om1_utils.healthcheck import HealthCheckServer
+
+
+def find_free_port() -> int:
+    """Find a free port on localhost."""
+    with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as sock:
+        sock.bind(("", 0))
+        sock.listen(1)
+        return sock.getsockname()[1]
+
+
+@pytest.fixture
+def server():
+    """Create and manage a HealthCheckServer for testing."""
+    port = find_free_port()
+    srv = HealthCheckServer(port=port)
+    srv.start()
+    time.sleep(0.3)
+    yield srv, port
+    srv.stop()
+    time.sleep(0.3)
+
+
+class TestHealthCheckServer:
+    """Tests for the HealthCheckServer class."""
+
+    def test_default_port(self):
+        """Test that default port is 9999."""
+        srv = HealthCheckServer()
+        assert srv.port == 9999
+
+    def test_custom_port(self):
+        """Test initialization with a custom port."""
+        srv = HealthCheckServer(port=8080)
+        assert srv.port == 8080
+
+    def test_initial_state(self):
+        """Test that server starts in non-running state."""
+        srv = HealthCheckServer()
+        assert srv.is_running() is False
+        assert srv.server is None
+        assert srv.server_thread is None
+
+    def test_start_sets_running(self, server):
+        """Test that start sets running to True."""
+        srv, _ = server
+        assert srv.is_running() is True
+
+    def test_stop_sets_not_running(self, server):
+        """Test that stop sets running to False."""
+        srv, _ = server
+        srv.stop()
+        assert srv.is_running() is False
+
+    def test_double_start_does_not_crash(self, server):
+        """Test that calling start twice does not raise an error."""
+        srv, _ = server
+        srv.start()
+        assert srv.is_running() is True
+
+    def test_get_returns_200(self, server):
+        """Test that GET request returns 200 OK."""
+        _, port = server
+        response = requests.get(f"http://127.0.0.1:{port}", timeout=5)
+        assert response.status_code == 200
+        assert response.text == "OK"
+
+    def test_stop_without_start(self):
+        """Test that stop on a never-started server does not crash."""
+        srv = HealthCheckServer()
+        srv.stop()
+        assert srv.is_running() is False