test: make event-loop release gate deterministic (Closes #884)

tests/test_dashboard_auth.py

@@ -1860,9 +1860,14 @@ async def test_session_registry_latency_does_not_block_the_event_loop(access_con
 async def test_sign_in_throttle_lookup_does_not_block_the_event_loop(
     access_control, monkeypatch
 ):
+    lookup_started = threading.Event()
+    lookup_finished = threading.Event()
+
     class SlowAttempts:
         def retry_after(self, source):
-            time.sleep(0.15)
+            lookup_started.set()
+            time.sleep(0.3)
+            lookup_finished.set()
             return 17
 
         def record_blocked(self, *, method):
@@ -1874,15 +1879,13 @@ async def test_sign_in_throttle_lookup_does_not_block_the_event_loop(
         sign_in = asyncio.create_task(
             client.post("/api/v1/session", json={"access_token": "wrong"})
         )
-        await asyncio.sleep(0)
-        started = time.perf_counter()
+        assert await asyncio.to_thread(lookup_started.wait, 1)
         await asyncio.sleep(0.01)
-        heartbeat_elapsed = time.perf_counter() - started
+        assert not lookup_finished.is_set()
         response = await sign_in
 
     assert response.status_code == 429
     assert response.headers["retry-after"] == "17"
-    assert heartbeat_elapsed < 0.08
 
 
 @pytest.mark.anyio