test(proxy): isolate the agent read-through singleton between unknown-agent tests

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

tests/test_litellm/proxy/common_utils/test_registry_read_through.py

@@ -207,7 +207,9 @@ async def test_get_agent_with_read_through_recovers_agent_by_name(clean_agent_re
 
 
 @pytest.mark.asyncio
-async def test_get_agent_with_read_through_returns_none_for_unknown_agent(clean_agent_registry, monkeypatch):
+async def test_get_agent_with_read_through_returns_none_for_unknown_agent(
+    clean_agent_registry, fresh_agent_read_through, monkeypatch
+):
     from unittest.mock import AsyncMock, MagicMock
 
     import litellm.proxy.proxy_server as proxy_server

tests/test_litellm/proxy/conftest.py

@@ -273,3 +273,12 @@ def create_proxy_test_client(
     # Initialize proxy
     asyncio.run(initialize(config=config_fp, debug=init_options.get("debug", False)))
     return TestClient(app)
+
+
+@pytest.fixture
+def fresh_agent_read_through(monkeypatch):
+    from litellm.proxy.common_utils import registry_read_through
+
+    read_through = registry_read_through.RegistryReadThrough(resync=registry_read_through._resync_agents)
+    monkeypatch.setattr(registry_read_through, "agent_registry_read_through", read_through)
+    return read_through

tests/test_litellm/proxy/test_route_llm_request.py

@@ -1282,7 +1282,7 @@ async def test_route_request_routing_group_name_passes_model_gate():
 
 
 @pytest.mark.asyncio
-async def test_route_request_a2a_agent_miss_does_not_consume_model_read_through(monkeypatch):
+async def test_route_request_a2a_agent_miss_does_not_consume_model_read_through(fresh_agent_read_through, monkeypatch):
     from types import SimpleNamespace
     from unittest.mock import AsyncMock