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test: eliminate test_get_info_single race by injecting from the send mock #1716

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Merged
bdraco merged 1 commit into from
May 18, 2026
Merged

test: eliminate test_get_info_single race by injecting from the send mock #1716

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141 changes: 66 additions & 75 deletions tests/services/test_info.py
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Original file line number Diff line number Diff line change
Expand Up @@ -522,97 +522,88 @@ def test_get_info_single(self):
service_address = "10.0.1.2"

service_info = None
send_event = Event()
service_info_event = Event()

last_sent: r.DNSOutgoing | None = None
ttl = 120
response_records = [
r.DNSText(
service_name,
const._TYPE_TXT,
const._CLASS_IN | const._CLASS_UNIQUE,
ttl,
service_text,
),
r.DNSService(
service_name,
const._TYPE_SRV,
const._CLASS_IN | const._CLASS_UNIQUE,
ttl,
0,
0,
80,
service_server,
),
r.DNSAddress(
service_server,
const._TYPE_A,
const._CLASS_IN | const._CLASS_UNIQUE,
ttl,
socket.inet_pton(socket.AF_INET, service_address),
),
]

def send(out, addr=const._MDNS_ADDR, port=const._MDNS_PORT, v6_flow_scope=()):
"""Sends an outgoing packet."""
nonlocal last_sent
def mock_incoming_msg(records: Iterable[r.DNSRecord]) -> r.DNSIncoming:
generated = r.DNSOutgoing(const._FLAGS_QR_RESPONSE)
for record in records:
generated.add_answer_at_time(record, 0)
return r.DNSIncoming(generated.packets()[0])

last_sent = out
send_event.set()
sent_queries: list[r.DNSOutgoing] = []

def send(out, addr=const._MDNS_ADDR, port=const._MDNS_PORT, v6_flow_scope=()):
"""Capture each query and, on the first one, fill the cache
inline so the next iteration of `async_request` finds
`_is_complete=True` and exits without sending another query.

Running the inject from inside `send` keeps it on the event
loop thread and atomic with the first send — eliminating the
test-thread → `run_coroutine_threadsafe` race that flaked
under PyPy + use_cython when `quick_request_timing` shortens
the inter-iteration delay to ~15ms.
"""
sent_queries.append(out)
if len(sent_queries) == 1:
zc.record_manager.async_updates_from_response(mock_incoming_msg(response_records))

def get_service_info_helper(zc, type, name):
nonlocal service_info
service_info = zc.get_service_info(type, name)
service_info_event.set()

# patch the zeroconf send
with patch.object(zc, "async_send", send):

def mock_incoming_msg(records: Iterable[r.DNSRecord]) -> r.DNSIncoming:
generated = r.DNSOutgoing(const._FLAGS_QR_RESPONSE)

for record in records:
generated.add_answer_at_time(record, 0)

return r.DNSIncoming(generated.packets()[0])

def get_service_info_helper(zc, type, name):
nonlocal service_info
service_info = zc.get_service_info(type, name)
service_info_event.set()

try:
ttl = 120
helper_thread = threading.Thread(
target=get_service_info_helper,
args=(zc, service_type, service_name),
)
helper_thread.start()
# Positive wait — the first query fires within
# `_LISTENER_TIME` + jitter (~15ms under
# `quick_request_timing`, ~320ms without).
wait_time = 1

# Expect query for SRV, TXT, A, AAAA
send_event.wait(wait_time)
assert last_sent is not None
assert len(last_sent.questions) == 4
assert r.DNSQuestion(service_name, const._TYPE_SRV, const._CLASS_IN) in last_sent.questions
assert r.DNSQuestion(service_name, const._TYPE_TXT, const._CLASS_IN) in last_sent.questions
assert r.DNSQuestion(service_name, const._TYPE_A, const._CLASS_IN) in last_sent.questions
assert r.DNSQuestion(service_name, const._TYPE_AAAA, const._CLASS_IN) in last_sent.questions
assert service_info is None

# Expect no further queries — under `quick_request_timing`
# the next query would have fired ~15ms after the previous
# send, so 100ms is plenty of headroom for the negative
# assertion.
last_sent = None
send_event.clear()
_inject_response(
zc,
mock_incoming_msg(
[
r.DNSText(
service_name,
const._TYPE_TXT,
const._CLASS_IN | const._CLASS_UNIQUE,
ttl,
service_text,
),
r.DNSService(
service_name,
const._TYPE_SRV,
const._CLASS_IN | const._CLASS_UNIQUE,
ttl,
0,
0,
80,
service_server,
),
r.DNSAddress(
service_server,
const._TYPE_A,
const._CLASS_IN | const._CLASS_UNIQUE,
ttl,
socket.inet_pton(socket.AF_INET, service_address),
),
]
),
)
send_event.wait(0.1)
assert last_sent is None
# Helper should complete promptly — the inline inject in
# `send` populates the cache before the request loop's
# next iteration.
service_info_event.wait(1)
assert service_info is not None

# First (and only) query: QU for SRV/TXT/A/AAAA.
assert len(sent_queries) == 1
first_sent = sent_queries[0]
assert len(first_sent.questions) == 4
assert r.DNSQuestion(service_name, const._TYPE_SRV, const._CLASS_IN) in first_sent.questions
assert r.DNSQuestion(service_name, const._TYPE_TXT, const._CLASS_IN) in first_sent.questions
assert r.DNSQuestion(service_name, const._TYPE_A, const._CLASS_IN) in first_sent.questions
assert r.DNSQuestion(service_name, const._TYPE_AAAA, const._CLASS_IN) in first_sent.questions

finally:
helper_thread.join()
zc.remove_all_service_listeners()
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