I am just wondering that how Miners got paid in Ropsten test net or other test nets?
Presently, Ropsten miners get paid in ether in the Ropsten blockchain for finding blocks, uncles, and transactions (via fees). The reward is currently the same number of Ropsten-ether as on the main net. Of course, Ropsten-ether isn't really worth much on the open market. The miners' incentives for Ropsten are basically to ensure they have enough ether to do whatever experiments they want to do, secure the network against nudniks, and test the consensus algorithm.
Unlike the main net, there is a much less direct economic incentive to mine on the Ropsten blockchain. You're indirectly helping improve the main net by testing the consensus algorithm and, presumably, also developing smart contracts which helps the main net ecosystem if/when they are deployed there. These can increase the value of ether held on the main net. Also, you gain a benefit from learning to write smart contracts without the same risk of costly mistakes as testing on the main net.
Other test nets have different rewards.