add a test for verifying getThreadManager is working correctly
add a test for verifying getThreadManager is working correctly

Summary: ^

Reviewed By: roddym

Differential Revision: D36293497

fbshipit-source-id: 0f61e7f8cabc5aa76eeac357e3e93e585ce40235

facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift