fix: remove unused anyio import, add pragma:no-branch for 3.10 compat, add multi-failure test

Author: g97iulio1609

src/mcp/client/_memory.py

@@ -7,8 +7,6 @@
 from types import TracebackType
 from typing import Any
 
-import anyio
-
 from mcp.client._transport import TransportStreams
 from mcp.server import Server
 from mcp.server.mcpserver import MCPServer

src/mcp/shared/_exception_utils.py

@@ -14,7 +14,7 @@
 import anyio
 from anyio.abc import TaskGroup
 
-if sys.version_info < (3, 11):
+if sys.version_info < (3, 11):  # pragma: no branch
     from exceptiongroup import BaseExceptionGroup
 
 

src/mcp/shared/session.py

@@ -12,7 +12,7 @@
 from pydantic import BaseModel, TypeAdapter
 from typing_extensions import Self
 
-if sys.version_info < (3, 11):
+if sys.version_info < (3, 11):  # pragma: no branch
     from exceptiongroup import BaseExceptionGroup
 
 from mcp.shared._exception_utils import collapse_exception_group

tests/shared/test_exception_utils.py

@@ -5,7 +5,7 @@
 import anyio
 import pytest
 
-if sys.version_info < (3, 11):
+if sys.version_info < (3, 11):  # pragma: no branch
     from exceptiongroup import BaseExceptionGroup
 
 from mcp.shared._exception_utils import collapse_exception_group, create_task_group
@@ -115,3 +115,18 @@ async def long_task() -> None:
                 tg.start_soon(long_task)
 
         assert isinstance(exc_info.value.__cause__, BaseExceptionGroup)
+
+    @pytest.mark.anyio
+    async def test_multiple_failures_raises_group(self) -> None:
+        """Multiple real task failures should raise as a BaseExceptionGroup."""
+        with pytest.raises(BaseExceptionGroup):
+            async with create_task_group() as tg:
+
+                async def fail_a() -> None:
+                    raise RuntimeError("error A")
+
+                async def fail_b() -> None:
+                    raise ValueError("error B")
+
+                tg.start_soon(fail_a)
+                tg.start_soon(fail_b)