Simplify test_session_group.py mocking

Remove complex mocking of create_mcp_http_client in the streamablehttp
test case. Instead, let the real create_mcp_http_client execute and
only verify that streamable_http_client receives the correct parameters
including a real httpx.AsyncClient instance.

This simplifies the test by:
- Removing 13 lines of mock setup code
- Removing 14 lines of mock verification code
- Removing 3 lines of mock cleanup code
- Trusting that create_mcp_http_client works (it has its own tests)

The test now focuses on verifying the integration between session_group
and streamable_http_client rather than re-testing create_mcp_http_client.

Author: felixweinberger

tests/client/test_session_group.py

@@ -292,20 +292,6 @@ async def test_establish_session_parameterized(
     ):
         with mock.patch("mcp.client.session_group.mcp.ClientSession") as mock_ClientSession_class:
             with mock.patch(patch_target_for_client_func) as mock_specific_client_func:
-                # For streamablehttp, also need to mock create_mcp_http_client
-                if client_type_name == "streamablehttp":
-                    mock_create_http_client = mock.patch("mcp.client.session_group.create_mcp_http_client")
-                    mock_create_http_client_func = mock_create_http_client.start()
-                    # Mock httpx_client returned by create_mcp_http_client
-                    mock_httpx_client = mock.AsyncMock(name="MockHttpxClient")
-                    mock_httpx_client.__aenter__.return_value = mock_httpx_client
-                    mock_httpx_client.__aexit__ = mock.AsyncMock(return_value=None)
-                    mock_create_http_client_func.return_value = mock_httpx_client
-                else:
-                    mock_create_http_client = None
-                    mock_create_http_client_func = None
-                    mock_httpx_client = None
-
                 mock_client_cm_instance = mock.AsyncMock(name=f"{client_type_name}ClientCM")
                 mock_read_stream = mock.AsyncMock(name=f"{client_type_name}Read")
                 mock_write_stream = mock.AsyncMock(name=f"{client_type_name}Write")
@@ -368,24 +354,14 @@ async def test_establish_session_parameterized(
                     )
                 elif client_type_name == "streamablehttp":  # pragma: no branch
                     assert isinstance(server_params_instance, StreamableHttpParameters)
-                    # Verify create_mcp_http_client was called with headers and timeout
+                    # Verify streamable_http_client was called with url, httpx_client, and terminate_on_close
+                    # The httpx_client is created by the real create_mcp_http_client
                     import httpx
 
-                    assert mock_create_http_client_func is not None
-                    expected_timeout = httpx.Timeout(
-                        server_params_instance.timeout.total_seconds(),
-                        read=server_params_instance.sse_read_timeout.total_seconds(),
-                    )
-                    mock_create_http_client_func.assert_called_once_with(
-                        headers=server_params_instance.headers,
-                        timeout=expected_timeout,
-                    )
-                    # Verify streamable_http_client was called with url, httpx_client, and terminate_on_close
-                    mock_specific_client_func.assert_called_once_with(
-                        url=server_params_instance.url,
-                        httpx_client=mock_httpx_client,
-                        terminate_on_close=server_params_instance.terminate_on_close,
-                    )
+                    call_args = mock_specific_client_func.call_args
+                    assert call_args.kwargs["url"] == server_params_instance.url
+                    assert call_args.kwargs["terminate_on_close"] == server_params_instance.terminate_on_close
+                    assert isinstance(call_args.kwargs["httpx_client"], httpx.AsyncClient)
 
                 mock_client_cm_instance.__aenter__.assert_awaited_once()
 
@@ -407,7 +383,3 @@ async def test_establish_session_parameterized(
                 # 3. Assert returned values
                 assert returned_server_info is mock_initialize_result.serverInfo
                 assert returned_session is mock_entered_session
-
-                # Clean up streamablehttp-specific mock
-                if mock_create_http_client:
-                    mock_create_http_client.stop()