Fix hanging on streams when stdio_client exiting

src/mcp/client/stdio/__init__.py

@@ -177,6 +177,8 @@ async def stdin_writer():
                 await terminate_windows_process(process)
             else:
                 process.terminate()
+            read_stream.close()
+            write_stream.close()
 
 
 def _get_executable_command(command: str) -> str:

tests/client/test_stdio.py

@@ -8,6 +8,13 @@
 tee: str = shutil.which("tee")  # type: ignore
 
 
+@pytest.mark.anyio
+@pytest.mark.skipif(tee is None, reason="could not find tee command")
+async def test_stdio_context_manager_exiting():
+    async with stdio_client(StdioServerParameters(command=tee)) as (_, _):
+        pass
+
+
 @pytest.mark.anyio
 @pytest.mark.skipif(tee is None, reason="could not find tee command")
 async def test_stdio_client():