t.Errorf("roundTrip = %#v, %v; want errServerClosedIdle, transportReadFromServerError, or nothingWrittenError", err, err)
	}

	<-pc.closech
	err = pc.closed
	if !isNothingWrittenError(err) && !isTransportReadFromServerError(err) && err != errServerClosedIdle {
		t.Errorf("pc.closed = %#v, %v; want errServerClosedIdle or transportReadFromServerError, or nothingWrittenError", err, err)
	}
}

func isNothingWrittenError(err error) bool {