test(scanner): reject unobserved enumeration budget evidence

Co-Authored-By: heihutu <heihutu@gmail.com>
Co-Authored-By: zhi22915 <qiuzgang@gmail.com>

scripts/diagnose_scanner_enumeration_restart.py

@@ -33,6 +33,8 @@ def validate_report(report, *, round_number, pid, objects, budget):
                 "versions_retained", "bytes_retained", "objects_processed"):
         if type(report.get(key)) is not int or not 0 <= report[key] <= 1048576:
             raise ValueError(f"invalid bounded counter: {key}")
+    if report["raw_entries"] == 0:
+        raise ValueError("nonempty fixture must observe raw entries; budget hook may not have run")
     if report["raw_entries"] > budget:
         raise ValueError("raw-entry budget exceeded; no unbudgeted tail is permitted")
     if type(report.get("snapshot_complete")) is not bool:

scripts/test_diagnose_scanner_enumeration_restart.py

@@ -42,6 +42,12 @@ class ReportTests(unittest.TestCase):
         with self.assertRaises(ValueError):
             self.validate(report)
 
+    def test_complete_coverage_without_entry_observation_rejected(self):
+        report = self.report()
+        report["raw_entries"] = 0
+        with self.assertRaises(ValueError):
+            self.validate(report)
+
     def test_missing_wrong_type_and_negative_counter_rejected(self):
         for value in (None, True, -1, "8", 1048577):
             with self.subTest(value=value):