Contract Lifecycle: Design, Development, and Deployment BDC Practice Questions (Page 3)

Questions 11–15

1. 11application · medium

   A team is starting a new Solidity project and wants a development environment that supports automated testing, scriptable deployments, and local network simulation. They also need to manage multiple project dependencies and compile with different Solidity versions. Which toolchain should they choose?

   • AA text editor with the solc compiler only
   • BRemix IDE with the JavaScript VM
   • CHardhat with its built-in local network and plugin ecosystem
   • DGanache CLI with a custom deployment script
   Reveal Solution Discussion Select an answer first
2. 12application · medium

   A developer wants to deploy a contract to the Ethereum mainnet using Hardhat. Which configuration is required in `hardhat.config.js`?

   • AA `mocha` object with test timeout settings.
   • BA `paths` object specifying the deployment scripts folder.
   • CA `networks` object with `mainnet` containing `url` and `accounts` (private key or mnemonic).
   • DA `compilers` object with `solc` version only.
   Reveal Solution Discussion Select an answer first
4. 13application · medium

   A developer is writing a Solidity function that should only be callable by the contract owner and should also be able to receive Ether. Which function declaration is correct?

   • Afunction withdraw() external onlyOwner payable { ... }
   • Bfunction withdraw() private onlyOwner payable { ... }
   • Cfunction withdraw() internal onlyOwner payable { ... }
   • Dfunction withdraw() public onlyOwner { ... }
   Reveal Solution Discussion Select an answer first
5. 14expert · hard

   A team has an upgradeable proxy contract that has been live for a year. They need to add a new state variable to the implementation contract. What is the most important consideration?

   • AInsert the new variable in the middle of the existing variables to group related data.
   • BRemove an unused variable to make room for the new one.
   • CUse the same variable name as an existing one to save storage.
   • DAppend the new variable at the end of the storage layout to avoid overwriting existing variables.
   Reveal Solution Discussion Select an answer first
6. 15expert · hard

   A developer is setting up a CI/CD pipeline for a Solidity project. They need to run tests automatically on every commit. The project uses Hardhat and has a `test` script in `package.json`. Which configuration is most appropriate for the pipeline?

   • ARun `npx hardhat compile` only, to check for compilation errors
   • BRun `npm test` in a Node.js environment with the project dependencies installed
   • CRun `npx hardhat deploy --network mainnet` to test on mainnet
   • DRun `npx hardhat node` and then manually test in a browser
   Reveal Solution Discussion Select an answer first