test: shave ServiceBrowser first-query delay on loopback

bluetoothbot · bluetoothbot · commit 76c31a763003 · 2026-05-18T03:37:10.000Z
`ServiceBrowser` waits `random.randint(20, 120)` ms before its first query — RFC 6762 §5.2 thundering-herd avoidance for real networks, pure overhead on 127.0.0.1. Every browser-using test pays it, and `ZeroconfServiceTypes.find()` adds it on top of `time.sleep(timeout)` because find() doesn't short-circuit on the first response. Extend `quick_timing` to also patch `_FIRST_QUERY_DELAY_RANDOM_INTERVAL` to (1, 5) ms, drop `LOOPBACK_FIND_TIMEOUT` from 200 → 75 ms (still ~7x headroom over the ~10 ms response latency on loopback), and apply `quick_timing` to the four `test_integration_with_*` tests in tests/services/test_types.py. Numbers on a local run: test_integration_with_listener 0.67s → 0.20s test_integration_with_listener_v6_records 0.69s → 0.19s test_integration_with_subtype_and_listener 0.68s → 0.19s test_integration_with_listener_ipv6 0.69s → 0.20s test_async_zeroconf_service_types 0.74s → 0.55s Full suite: 48.78s → 42.94s (-12%). Part of #1707.
diff --git a/tests/__init__.py b/tests/__init__.py
@@ -45,9 +45,11 @@
 # Timeout for ZeroconfServiceTypes.find() / AsyncZeroconfServiceTypes.async_find()
 # in loopback integration tests. `find()` is just `time.sleep(timeout)` —
 # it doesn't short-circuit on the first matching response — so the
-# timeout becomes a lower bound on the test runtime. On loopback the
-# registrar's response lands within a few ms; 200ms is ~50x headroom.
-LOOPBACK_FIND_TIMEOUT = 0.2
+# timeout becomes a lower bound on the test runtime. Callers MUST use
+# the `quick_timing` fixture, which shrinks the browser's first-query
+# delay from RFC 6762 §5.2's 20-120ms window to 1-5ms; with that shave
+# the registrar's response lands inside ~10ms and 75ms is ~7x headroom.
+LOOPBACK_FIND_TIMEOUT = 0.075
 
 
 class QuestionHistoryWithoutSuppression(QuestionHistory):
diff --git a/tests/conftest.py b/tests/conftest.py
@@ -10,6 +10,7 @@
 
 from zeroconf import _core, const
 from zeroconf._handlers import query_handler
+from zeroconf._services import browser as service_browser
 from zeroconf._services import info as service_info
 
 
@@ -46,18 +47,21 @@ def disable_duplicate_packet_suppression():
 
 @pytest.fixture
 def quick_timing() -> Generator[None]:
-    """Shorten the probe/announce/goodbye intervals for tests on loopback.
+    """Shorten the probe/announce/goodbye/first-query intervals for tests on loopback.
 
     The production values (_CHECK_TIME=500ms, _REGISTER_TIME=225ms,
-    _UNREGISTER_TIME=125ms) exist for RFC 6762 interop on real
-    networks. Tests on 127.0.0.1 do not need them and pay 1-2s per
-    register/unregister cycle without this fixture. Opt in by adding
-    `quick_timing` to a test's argument list.
+    _UNREGISTER_TIME=125ms, _FIRST_QUERY_DELAY_RANDOM_INTERVAL=20-120ms)
+    exist for RFC 6762 interop on real networks (§8.1 thundering-herd
+    avoidance for probing, §5.2 for the initial-query delay). Tests on
+    127.0.0.1 do not need them and pay 1-2s per register/unregister
+    cycle and 20-120ms per ServiceBrowser startup without this fixture.
+    Opt in by adding `quick_timing` to a test's argument list.
     """
     with (
         patch.object(_core, "_CHECK_TIME", 10),
         patch.object(_core, "_REGISTER_TIME", 10),
         patch.object(_core, "_UNREGISTER_TIME", 10),
+        patch.object(service_browser, "_FIRST_QUERY_DELAY_RANDOM_INTERVAL", (1, 5)),
     ):
         yield
 
diff --git a/tests/services/test_types.py b/tests/services/test_types.py
@@ -28,7 +28,7 @@ def teardown_module():
         log.setLevel(original_logging_level)
 
 
-def test_integration_with_listener(disable_duplicate_packet_suppression):
+def test_integration_with_listener(quick_timing, disable_duplicate_packet_suppression):
     type_ = "_test-listen-type._tcp.local."
     name = "xxxyyy"
     registration_name = f"{name}.{type_}"
@@ -59,7 +59,7 @@ def test_integration_with_listener(disable_duplicate_packet_suppression):
 
 @unittest.skipIf(not has_working_ipv6(), "Requires IPv6")
 @unittest.skipIf(os.environ.get("SKIP_IPV6"), "IPv6 tests disabled")
-def test_integration_with_listener_v6_records(disable_duplicate_packet_suppression):
+def test_integration_with_listener_v6_records(quick_timing, disable_duplicate_packet_suppression):
     type_ = "_test-listenv6rec-type._tcp.local."
     name = "xxxyyy"
     registration_name = f"{name}.{type_}"
@@ -95,7 +95,7 @@ def test_integration_with_listener_v6_records(disable_duplicate_packet_suppressi
     sys.platform == "darwin" and os.environ.get("GITHUB_ACTIONS") == "true",
     "IPv6 multicast not working on macOS GitHub Actions",
 )
-def test_integration_with_listener_ipv6(disable_duplicate_packet_suppression):
+def test_integration_with_listener_ipv6(quick_timing, disable_duplicate_packet_suppression):
     type_ = "_test-listenv6ip-type._tcp.local."
     name = "xxxyyy"
     registration_name = f"{name}.{type_}"
@@ -127,7 +127,7 @@ def test_integration_with_listener_ipv6(disable_duplicate_packet_suppression):
         zeroconf_registrar.close()
 
 
-def test_integration_with_subtype_and_listener(disable_duplicate_packet_suppression):
+def test_integration_with_subtype_and_listener(quick_timing, disable_duplicate_packet_suppression):
     subtype_ = "_subtype._sub"
     type_ = "_listen._tcp.local."
     name = "xxxyyy"
