fix(backend/mcp): Use httpx.AsyncClient in test_routes to prevent event loop corruption

Replace fastapi.testclient.TestClient with httpx.AsyncClient + ASGITransport.

TestClient creates a new anyio blocking portal per request. When 11+ portals
are created and destroyed in a session that also has pytest-asyncio session-scoped
async fixtures, the session event loop gets corrupted, causing
"RuntimeError: Event loop is closed" in subsequent async tests.

AsyncClient with ASGITransport runs the ASGI app directly in the current
event loop without creating blocking portals.

autogpt_platform/backend/backend/api/features/mcp/test_routes.py

@@ -1,9 +1,15 @@
-"""Tests for MCP API routes."""
+"""Tests for MCP API routes.
+
+Uses httpx.AsyncClient with ASGITransport instead of fastapi.testclient.TestClient
+to avoid creating blocking portals that can corrupt pytest-asyncio's session event loop.
+"""
 
 from unittest.mock import AsyncMock, patch
 
 import fastapi
-import fastapi.testclient
+import httpx
+import pytest
+import pytest_asyncio
 from autogpt_libs.auth import get_user_id
 
 from backend.api.features.mcp.routes import router
@@ -13,11 +19,18 @@ from backend.util.request import HTTPClientError
 app = fastapi.FastAPI()
 app.include_router(router)
 app.dependency_overrides[get_user_id] = lambda: "test-user-id"
-client = fastapi.testclient.TestClient(app)
+
+
+@pytest_asyncio.fixture(scope="module")
+async def client():
+    transport = httpx.ASGITransport(app=app)
+    async with httpx.AsyncClient(transport=transport, base_url="http://test") as c:
+        yield c
 
 
 class TestDiscoverTools:
-    def test_discover_tools_success(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_discover_tools_success(self, client):
         mock_tools = [
             MCPTool(
                 name="get_weather",
@@ -51,7 +64,7 @@ class TestDiscoverTools:
             )
             instance.list_tools = AsyncMock(return_value=mock_tools)
 
-            response = client.post(
+            response = await client.post(
                 "/discover-tools",
                 json={"server_url": "https://mcp.example.com/mcp"},
             )
@@ -64,7 +77,8 @@ class TestDiscoverTools:
         assert data["server_name"] == "test-server"
         assert data["protocol_version"] == "2025-03-26"
 
-    def test_discover_tools_with_auth_token(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_discover_tools_with_auth_token(self, client):
         with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
             instance = MockClient.return_value
             instance.initialize = AsyncMock(
@@ -72,7 +86,7 @@ class TestDiscoverTools:
             )
             instance.list_tools = AsyncMock(return_value=[])
 
-            response = client.post(
+            response = await client.post(
                 "/discover-tools",
                 json={
                     "server_url": "https://mcp.example.com/mcp",
@@ -86,7 +100,8 @@ class TestDiscoverTools:
             auth_token="my-secret-token",
         )
 
-    def test_discover_tools_auto_uses_stored_credential(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_discover_tools_auto_uses_stored_credential(self, client):
         """When no explicit token is given, stored MCP credentials are used."""
         from pydantic import SecretStr
 
@@ -115,7 +130,7 @@ class TestDiscoverTools:
             )
             instance.list_tools = AsyncMock(return_value=[])
 
-            response = client.post(
+            response = await client.post(
                 "/discover-tools",
                 json={"server_url": "https://mcp.example.com/mcp"},
             )
@@ -126,14 +141,15 @@ class TestDiscoverTools:
             auth_token="stored-token-123",
         )
 
-    def test_discover_tools_mcp_error(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_discover_tools_mcp_error(self, client):
         with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
             instance = MockClient.return_value
             instance.initialize = AsyncMock(
                 side_effect=MCPClientError("Connection refused")
             )
 
-            response = client.post(
+            response = await client.post(
                 "/discover-tools",
                 json={"server_url": "https://bad-server.example.com/mcp"},
             )
@@ -141,12 +157,13 @@ class TestDiscoverTools:
         assert response.status_code == 502
         assert "Connection refused" in response.json()["detail"]
 
-    def test_discover_tools_generic_error(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_discover_tools_generic_error(self, client):
         with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
             instance = MockClient.return_value
             instance.initialize = AsyncMock(side_effect=Exception("Network timeout"))
 
-            response = client.post(
+            response = await client.post(
                 "/discover-tools",
                 json={"server_url": "https://timeout.example.com/mcp"},
             )
@@ -154,14 +171,15 @@ class TestDiscoverTools:
         assert response.status_code == 502
         assert "Failed to connect" in response.json()["detail"]
 
-    def test_discover_tools_auth_required(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_discover_tools_auth_required(self, client):
         with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
             instance = MockClient.return_value
             instance.initialize = AsyncMock(
                 side_effect=HTTPClientError("HTTP 401 Error: Unauthorized", 401)
             )
 
-            response = client.post(
+            response = await client.post(
                 "/discover-tools",
                 json={"server_url": "https://auth-server.example.com/mcp"},
             )
@@ -169,14 +187,15 @@ class TestDiscoverTools:
         assert response.status_code == 401
         assert "requires authentication" in response.json()["detail"]
 
-    def test_discover_tools_forbidden(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_discover_tools_forbidden(self, client):
         with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
             instance = MockClient.return_value
             instance.initialize = AsyncMock(
                 side_effect=HTTPClientError("HTTP 403 Error: Forbidden", 403)
             )
 
-            response = client.post(
+            response = await client.post(
                 "/discover-tools",
                 json={"server_url": "https://auth-server.example.com/mcp"},
             )
@@ -184,13 +203,15 @@ class TestDiscoverTools:
         assert response.status_code == 401
         assert "requires authentication" in response.json()["detail"]
 
-    def test_discover_tools_missing_url(self):
-        response = client.post("/discover-tools", json={})
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_discover_tools_missing_url(self, client):
+        response = await client.post("/discover-tools", json={})
         assert response.status_code == 422
 
 
 class TestOAuthLogin:
-    def test_oauth_login_success(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_oauth_login_success(self, client):
         with (
             patch("backend.api.features.mcp.routes.MCPClient") as MockClient,
             patch("backend.api.features.mcp.routes.creds_manager") as mock_cm,
@@ -223,7 +244,7 @@ class TestOAuthLogin:
             )
             mock_settings.config.frontend_base_url = "http://localhost:3000"
 
-            response = client.post(
+            response = await client.post(
                 "/oauth/login",
                 json={"server_url": "https://mcp.sentry.dev/mcp"},
             )
@@ -235,13 +256,14 @@ class TestOAuthLogin:
         assert "auth.sentry.io/authorize" in data["login_url"]
         assert "registered-client-id" in data["login_url"]
 
-    def test_oauth_login_no_oauth_support(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_oauth_login_no_oauth_support(self, client):
         with patch("backend.api.features.mcp.routes.MCPClient") as MockClient:
             instance = MockClient.return_value
             instance.discover_auth = AsyncMock(return_value=None)
             instance.discover_auth_server_metadata = AsyncMock(return_value=None)
 
-            response = client.post(
+            response = await client.post(
                 "/oauth/login",
                 json={"server_url": "https://simple-server.example.com/mcp"},
             )
@@ -249,7 +271,8 @@ class TestOAuthLogin:
         assert response.status_code == 400
         assert "does not advertise OAuth" in response.json()["detail"]
 
-    def test_oauth_login_fallback_to_public_client(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_oauth_login_fallback_to_public_client(self, client):
         """When DCR is unavailable, falls back to default public client ID."""
         with (
             patch("backend.api.features.mcp.routes.MCPClient") as MockClient,
@@ -275,7 +298,7 @@ class TestOAuthLogin:
             )
             mock_settings.config.frontend_base_url = "http://localhost:3000"
 
-            response = client.post(
+            response = await client.post(
                 "/oauth/login",
                 json={"server_url": "https://mcp.example.com/mcp"},
             )
@@ -286,7 +309,8 @@ class TestOAuthLogin:
 
 
 class TestOAuthCallback:
-    def test_oauth_callback_success(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_oauth_callback_success(self, client):
         from pydantic import SecretStr
 
         from backend.data.model import OAuth2Credentials
@@ -334,7 +358,7 @@ class TestOAuthCallback:
             # Mock old credential cleanup
             mock_cm.store.get_creds_by_provider = AsyncMock(return_value=[])
 
-            response = client.post(
+            response = await client.post(
                 "/oauth/callback",
                 json={"code": "auth-code-abc", "state_token": "state-token-123"},
             )
@@ -346,11 +370,12 @@ class TestOAuthCallback:
         assert data["type"] == "oauth2"
         mock_cm.create.assert_called_once()
 
-    def test_oauth_callback_invalid_state(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_oauth_callback_invalid_state(self, client):
         with patch("backend.api.features.mcp.routes.creds_manager") as mock_cm:
             mock_cm.store.verify_state_token = AsyncMock(return_value=None)
 
-            response = client.post(
+            response = await client.post(
                 "/oauth/callback",
                 json={"code": "auth-code", "state_token": "bad-state"},
             )
@@ -358,7 +383,8 @@ class TestOAuthCallback:
         assert response.status_code == 400
         assert "Invalid or expired" in response.json()["detail"]
 
-    def test_oauth_callback_token_exchange_fails(self):
+    @pytest.mark.asyncio(loop_scope="session")
+    async def test_oauth_callback_token_exchange_fails(self, client):
         with (
             patch("backend.api.features.mcp.routes.creds_manager") as mock_cm,
             patch("backend.api.features.mcp.routes.settings") as mock_settings,
@@ -381,7 +407,7 @@ class TestOAuthCallback:
                 side_effect=RuntimeError("Token exchange failed")
             )
 
-            response = client.post(
+            response = await client.post(
                 "/oauth/callback",
                 json={"code": "bad-code", "state_token": "state"},
             )