test: pin _mark_seen FIFO eviction and add CodSpeed bench

bdraco · bdraco · commit 9a643536a61d · 2026-05-17T19:20:24.000-07:00
Tighten ``test_seen_logs_is_bounded`` to assert the cap is held
exactly and that the oldest 5 keys are evicted first while the newest
overflow keys remain — without this, the test would have passed for
``set.pop()`` (random eviction) too, hiding any future regression
away from dict-backed FIFO.

Also add ``tests/benchmarks/test_mark_seen.py`` so CodSpeed tracks
the three branches (hit / fill / churn) of the helper.
diff --git a/tests/benchmarks/test_mark_seen.py b/tests/benchmarks/test_mark_seen.py
@@ -0,0 +1,39 @@
+"""Benchmark for _logger._mark_seen."""
+
+from __future__ import annotations
+
+from pytest_codspeed import BenchmarkFixture
+
+from zeroconf._logger import _MAX_SEEN_LOGS, _mark_seen
+
+
+def test_mark_seen_hit(benchmark: BenchmarkFixture) -> None:
+    """Benchmark the cache-hit path (same key repeated)."""
+    seen: dict[str, None] = {"warm": None}
+
+    @benchmark
+    def _hit() -> None:
+        for _ in range(1000):
+            _mark_seen(seen, "warm")
+
+
+def test_mark_seen_fill(benchmark: BenchmarkFixture) -> None:
+    """Benchmark filling from empty up to the cap (no evictions)."""
+    keys = [f"key-{i}" for i in range(_MAX_SEEN_LOGS)]
+
+    @benchmark
+    def _fill() -> None:
+        seen: dict[str, None] = {}
+        for k in keys:
+            _mark_seen(seen, k)
+
+
+def test_mark_seen_churn(benchmark: BenchmarkFixture) -> None:
+    """Benchmark sustained eviction (every call past the cap drops oldest)."""
+    keys = [f"churn-{i}" for i in range(_MAX_SEEN_LOGS * 4)]
+
+    @benchmark
+    def _churn() -> None:
+        seen: dict[str, None] = {}
+        for k in keys:
+            _mark_seen(seen, k)
diff --git a/tests/test_logger.py b/tests/test_logger.py
@@ -85,13 +85,18 @@ def test_llog_exception_debug():
     assert mock_log_debug.mock_calls == [call("the exception", exc_info=False)]
 
 
-def test_seen_logs_is_bounded():
-    """Distinct keys must not grow ``_seen_logs`` without bound."""
+def test_seen_logs_is_bounded() -> None:
+    """``_seen_logs`` stays at the cap and evicts oldest-first (FIFO)."""
     _logger._seen_logs.clear()
+    overflow = 5
     with patch("zeroconf._logger.log.warning"), patch("zeroconf._logger.log.debug"):
-        for i in range(_MAX_SEEN_LOGS + 5):
+        for i in range(_MAX_SEEN_LOGS + overflow):
             QuietLogger.log_warning_once(f"warning-{i}")
-    assert len(_logger._seen_logs) <= _MAX_SEEN_LOGS
+    assert len(_logger._seen_logs) == _MAX_SEEN_LOGS
+    for i in range(overflow):
+        assert f"warning-{i}" not in _logger._seen_logs
+    for i in range(_MAX_SEEN_LOGS, _MAX_SEEN_LOGS + overflow):
+        assert f"warning-{i}" in _logger._seen_logs
 
 
 def test_log_exception_once():
