feat: add _build_host_info helper for host info endpoint

Extracts host info assembly (owner, managers, hbc version/type,
last packet timestamp, threshold configs) into a testable module-level
helper, with 10 covering tests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_http_host_info.py

@@ -0,0 +1,129 @@
+"""Tests for _build_host_info helper in http.py."""
+import pytest
+from unittest.mock import MagicMock
+from hbd.server.http import _build_host_info
+
+
+class _FakeConn:
+    def __init__(self, lastbeat):
+        self.lastbeat = lastbeat
+
+
+class _FakeHost:
+    def __init__(self, name="myhost", owner=None, managers=None,
+                 connections=None, os_data=None):
+        self.name = name
+        self.owner = owner
+        self.managers = managers or []
+        self.connections = connections or {}
+        self._os_data = os_data
+
+    def get_latest_plugin_data(self, plugin_name):
+        if plugin_name == "os_info" and self._os_data is not None:
+            return (1234567890.0, self._os_data)
+        return None
+
+
+def test_build_host_info_basic_fields():
+    host = _FakeHost(owner="alice", managers=["bob", "carol"])
+    result = _build_host_info(host)
+    assert result["owner"] == "alice"
+    assert result["managers"] == ["bob", "carol"]
+    assert result["hbc_version"] is None
+    assert result["hbc_type"] is None
+    assert result["last_packet"] is None
+    assert result["thresholds"] is None
+
+
+def test_build_host_info_no_owner():
+    host = _FakeHost()
+    result = _build_host_info(host)
+    assert result["owner"] is None
+    assert result["managers"] == []
+
+
+def test_build_host_info_reads_hbc_from_os_info():
+    host = _FakeHost(os_data={"hbc_version": "5.3.0", "hbc_type": "full"})
+    result = _build_host_info(host)
+    assert result["hbc_version"] == "5.3.0"
+    assert result["hbc_type"] == "full"
+
+
+def test_build_host_info_hbc_none_when_no_os_info():
+    host = _FakeHost(os_data=None)
+    result = _build_host_info(host)
+    assert result["hbc_version"] is None
+    assert result["hbc_type"] is None
+
+
+def test_build_host_info_last_packet_is_max_lastbeat():
+    host = _FakeHost(connections={
+        "IPv4": _FakeConn(1000.0),
+        "IPv6": _FakeConn(2000.0),
+    })
+    result = _build_host_info(host)
+    assert result["last_packet"] == 2000.0
+
+
+def test_build_host_info_last_packet_none_when_no_connections():
+    host = _FakeHost(connections={})
+    result = _build_host_info(host)
+    assert result["last_packet"] is None
+
+
+def test_build_host_info_thresholds_none_without_checker():
+    host = _FakeHost()
+    result = _build_host_info(host, threshold_checker=None)
+    assert result["thresholds"] is None
+
+
+def test_build_host_info_thresholds_sorted_by_metric():
+    from hbd.server.threshold import ThresholdConfig
+    tc_cpu = ThresholdConfig("cpu_monitor.cpu_percent", warning=80.0, critical=95.0)
+    tc_mem = ThresholdConfig("memory_monitor.memory_percent", warning=85.0, critical=98.0)
+
+    checker = MagicMock()
+    checker.get_thresholds_for_host.return_value = {
+        "memory_monitor.memory_percent": tc_mem,
+        "cpu_monitor.cpu_percent": tc_cpu,
+    }
+
+    host = _FakeHost()
+    result = _build_host_info(host, threshold_checker=checker)
+
+    assert result["thresholds"] is not None
+    assert len(result["thresholds"]) == 2
+    assert result["thresholds"][0]["metric"] == "cpu_monitor.cpu_percent"
+    assert result["thresholds"][0]["warning"] == 80.0
+    assert result["thresholds"][0]["critical"] == 95.0
+    assert result["thresholds"][0]["operator"] == ">"
+    assert result["thresholds"][1]["metric"] == "memory_monitor.memory_percent"
+
+
+def test_build_host_info_thresholds_empty_list_when_no_thresholds():
+    checker = MagicMock()
+    checker.get_thresholds_for_host.return_value = {}
+    host = _FakeHost()
+    result = _build_host_info(host, threshold_checker=checker)
+    assert result["thresholds"] == []
+
+
+def test_build_host_info_threshold_null_warning_critical():
+    from hbd.server.threshold import ThresholdConfig
+    tc = ThresholdConfig("rtt.myhost", warning=None, critical=500.0)
+    checker = MagicMock()
+    checker.get_thresholds_for_host.return_value = {"rtt.myhost": tc}
+    host = _FakeHost()
+    result = _build_host_info(host, threshold_checker=checker)
+    assert result["thresholds"][0]["warning"] is None
+    assert result["thresholds"][0]["critical"] == 500.0
+
+
+def test_build_host_info_nagios_operator_serialized():
+    from hbd.server.threshold import ThresholdConfig
+    tc = ThresholdConfig("nagios_runner.check_http", operator="nagios")
+    checker = MagicMock()
+    checker.get_thresholds_for_host.return_value = {"nagios_runner.check_http": tc}
+    host = _FakeHost()
+    result = _build_host_info(host, threshold_checker=checker)
+    assert result["thresholds"][0]["operator"] == "nagios"