You need real Ether for deploying a smart contract in the Ethereum mainnet, however, for deploying in Ropsten you need to get Ropsten test Ether. This is an Ethereum JavaScript API. Web3. js library allows you to interact with a local or remote Ethereum node.
I do not think it is practicable to test DApp or Smart contract with Ether. It is not only Ethereum that runs on a DApp or smartcontract! There are myriad of chain networks that allow projects to run and be developed on them and to do this effectively the developer and network manager introduce native token as means of settlement to cover fees for making use of the network.
Therefore, I can conclude that Ethereum is just a fee or currency that finds its use cases through deployment of smartcontract on Ethereum network or DApp attached to Defi programs run on Ether network. Consequently, if there is no project involving use of DApp or smartcontract connected to the network there would be no use of Ethereum. In fact you don't use Ether to test DApp or smartcontract you only need Ether to pay network fee associated for making use of the network.
Ever since Ethereum was introduced in the blockchain space with its presence in 2015, the invention by Vitalik Buterin, Canadian-Russian programmer has brought forth new decentralized applications (dApps). However, Ethereum’s success is significantly attributed to the implementation of smart contracts.