After searching quite a bit, finally I found my solution. Google don't provide subscription order number for test purchases(if you are using test account to test your application without going to production). It only provide product_id, token, purchase_time, developer_payload, autoRenewing, package_name and purchase_state as if Google don't send details to Play Billing server as it is not a real purchase. Still your can implement your own logic as it provide autoRenewing = true(if product is in renewal state) and false(if product is in non-renewal state) with purchase_state = 0(purchased) , 1(canceled) and 2(refunded). And one more thing I came to know after reading documentation of Google that, test user who has taken the subscriptions the recur on daily basis, but they will only get the same details, which they get while purchasing a test subscription plan.
It provide order Id for real purchases with other details. If your subscription is monthly and your order Id is GPA.1234-5678-9012-34567 while purchasing the plan. Then next month Google append your order Id with GPA.1234-5678-9012-34567..0(second month) , GPA.1234-5678-9012-34567..1 (third month) and so on. So you can track your renewal of purchases with order Id as described in here. Rest are same.