backport: coverage — reset sse-starlette's module-global exit Event between tests

sse-starlette <3.0 stores an anyio.Event on AppStatus the first time an
EventSourceResponse runs, bound to that test's event loop. Under the in-process
bridge (one process, per-test event loops) every subsequent SSE response — both
the [sse] leg and connect_with_oauth's streamable-HTTP responses — fails with
'bound to a different event loop'. v1's own transport tests run uvicorn in a
subprocess and so never share a process across event loops.

The previous commit's >=2.1.0 dev floor was insufficient (2.1.0 still has the
class attribute; 3.x switched to a ContextVar). An autouse fixture that resets
the attribute after each test handles all versions including the 1.6.1 runtime
floor, so the dev floor is reverted and lowest-direct CI again exercises the
runtime constraint.

Verified: 1598 tests / 100.00% coverage on both highest and lowest-direct.

Author: maxisbey

pyproject.toml

@@ -63,11 +63,6 @@ dev = [
     "inline-snapshot>=0.23.0",
     "dirty-equals>=0.9.0",
     "coverage[toml]==7.10.7",
-    # tests/interaction runs the streamable-HTTP and SSE apps in-process; sse-starlette 1.x
-    # keeps a module-global anyio.Event (`AppStatus.should_exit_event`) bound to the first
-    # test's event loop, which breaks every subsequent in-process SSE response. The runtime
-    # floor stays >=1.6.1 (works under uvicorn); only the test environment needs >=2.x.
-    "sse-starlette>=2.1.0",
 ]
 docs = [
     "mkdocs>=1.6.1",

tests/interaction/conftest.py

@@ -1,6 +1,9 @@
 """Shared fixtures for the interaction suite."""
 
+from collections.abc import Iterator
+
 import pytest
+from sse_starlette.sse import AppStatus
 
 from tests.interaction._connect import Connect, connect_in_memory, connect_over_sse, connect_over_streamable_http
 
@@ -29,6 +32,22 @@ def pytest_configure(config: pytest.Config) -> None:
 }
 
 
+@pytest.fixture(autouse=True)
+def _reset_sse_starlette_exit_event() -> Iterator[None]:
+    """Reset sse-starlette's module-global exit Event after each test.
+
+    sse-starlette <3.0 stores an `anyio.Event` on the `AppStatus` class the first time an
+    `EventSourceResponse` runs; that Event is bound to the test's event loop and breaks every
+    subsequent in-process SSE response (RuntimeError "bound to a different event loop", surfacing
+    as 5-second timeouts in `connect_with_oauth` and "Child exited" on the [sse] leg). v1's own
+    transport tests run uvicorn in a subprocess and so never share a process across event loops.
+    sse-starlette 3.x switched to a ContextVar (`_exit_event_context`) and has no such attribute.
+    """
+    yield
+    if hasattr(AppStatus, "should_exit_event"):  # pragma: no branch
+        AppStatus.should_exit_event = None  # pragma: lax no cover
+
+
 @pytest.fixture(params=sorted(_FACTORIES))
 def connect(request: pytest.FixtureRequest) -> Connect:
     """The transport-parametrized connection factory: a test using it runs once per transport.