fix: safely parse metric labels (#948)

tests/unit/test_query/test_ontology_monitoring.py

@@ -0,0 +1,73 @@
+"""
+Tests for ontology monitoring metrics.
+"""
+
+import importlib.util
+import sys
+from pathlib import Path
+
+
+MODULE_PATH = (
+    Path(__file__).resolve().parents[3]
+    / "trustgraph-flow"
+    / "trustgraph"
+    / "query"
+    / "ontology"
+    / "monitoring.py"
+)
+spec = importlib.util.spec_from_file_location("ontology_monitoring", MODULE_PATH)
+assert spec is not None and spec.loader is not None
+monitoring = importlib.util.module_from_spec(spec)
+sys.modules[spec.name] = monitoring
+spec.loader.exec_module(monitoring)
+
+PerformanceMonitor = monitoring.PerformanceMonitor
+_extract_metric_label = monitoring._extract_metric_label
+
+
+def test_extract_metric_label_reads_unquoted_label_value():
+    metric_name = "cache_requests_total{cache_type=entity,component=ontology}"
+
+    assert _extract_metric_label(metric_name, "cache_type") == "entity"
+
+
+def test_extract_metric_label_reads_quoted_label_value():
+    metric_name = 'cache_requests_total{cache_type="entity",component="ontology"}'
+
+    assert _extract_metric_label(metric_name, "cache_type") == "entity"
+
+
+def test_extract_metric_label_returns_none_when_label_missing():
+    metric_name = "cache_requests_total{component=ontology}"
+
+    assert _extract_metric_label(metric_name, "cache_type") is None
+
+
+def test_performance_report_ignores_counters_without_cache_type_label():
+    monitor = PerformanceMonitor({"enabled": False})
+    monitor.metrics_collector.increment(
+        "cache_requests_total",
+        labels={"component": "ontology"},
+    )
+    monitor.metrics_collector.increment(
+        "cache_type=not_a_label",
+        labels={"component": "ontology"},
+    )
+    monitor.metrics_collector.increment(
+        "cache_requests_total",
+        labels={"cache_type": "entity"},
+    )
+    monitor.metrics_collector.increment(
+        "cache_hits_total",
+        labels={"cache_type": "entity"},
+    )
+
+    report = monitor.get_performance_report()
+
+    assert report["cache_performance"] == {
+        "entity": {
+            "hit_rate": 1.0,
+            "total_requests": 1.0,
+            "total_hits": 1.0,
+        }
+    }