def slow_sync_stream():
    yield {"n": 1}
    time.sleep(0.3)
    yield {"n": 2}


def test_keepalive_ping_async(monkeypatch: pytest.MonkeyPatch):
    monkeypatch.setattr(fastapi.routing, "_PING_INTERVAL", 0.05)
    with TestClient(keepalive_app) as c:
        response = c.get("/slow-async")
    assert response.status_code == 200
    text = response.text

# Keep-alive comment, per the SSE spec recommendation
KEEPALIVE_COMMENT = b": ping\n\n"

# Seconds between keep-alive pings when a generator is idle.
# Private but importable so tests can monkeypatch it.

from fastapi.exceptions import (
    EndpointContext,
    FastAPIError,
    RequestValidationError,
    ResponseValidationError,
    WebSocketRequestValidationError,
)
from fastapi.sse import (
    _PING_INTERVAL,
    KEEPALIVE_COMMENT,
    EventSourceResponse,
    ServerSentEvent,
    format_sse_event,
)
from fastapi.types import DecoratedCallable, IncEx
from fastapi.utils import (
    create_model_field,