Testing, Debugging, and Auditing Contracts BDC Practice Questions (Page 2)

Questions 6–10

1. 6foundation · easy

   Which tool is commonly used to debug Solidity smart contracts by allowing step-by-step execution and inspection of variables?

   • AMetaMask
   • BGanache
   • CRemix IDE's debugger
   • DSolidity Compiler
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2. 7expert · hard

   A developer has used a static analysis tool and it reported a potential reentrancy vulnerability in a function. The developer manually reviewed the code and believes the vulnerability is not exploitable because the function uses a `require` statement that checks a condition before the external call. However, the external call is made before the state update. What should the developer do?

   • AIgnore the finding because static analysis tools often produce false positives.
   • BAdd a reentrancy guard to the function without changing the order of operations.
   • CDismiss the finding because the require check prevents the reentrancy.
   • DTreat the finding as valid and refactor the function to update the state before the external call, even if the require check seems sufficient.
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4. 8foundation · easy

   In TDD, what should you do after writing a test that fails?

   • ADelete the test and start over.
   • BRefactor the test to make it pass without changing the code.
   • CDeploy the contract to the mainnet to test it in production.
   • DWrite the simplest code that makes the test pass.
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5. 9application · medium

   A developer is writing tests for a contract that uses `block.timestamp` to determine if a sale has ended. The developer wants to test the behavior both before and after the sale deadline. Which testing technique is most appropriate?

   • ADeploy the contract to a public testnet and wait for the deadline to pass.
   • BUse a static analysis tool to verify the contract's time-based logic.
   • CWrite a unit test that calls the function with a hardcoded timestamp argument.
   • DUse a testing framework that allows manipulating the block timestamp, such as Hardhat's `evm_increaseTime` or Ganache's `evm_increaseTime`.
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6. 10expert · hard

   A developer is debugging a contract that behaves differently on the mainnet than in local tests. The contract uses `block.timestamp` and `block.number` in its logic. The developer suspects that the difference is due to the block parameters. Which debugging technique would best help reproduce the mainnet behavior locally?

   • ADeploy the contract to a test network that has similar block times to the mainnet.
   • BAdd `console.log` statements to print the values of `block.timestamp` and `block.number` in the contract.
   • CUse a testing framework that allows overriding `block.timestamp` and `block.number` in the local test environment to simulate the mainnet conditions.
   • DUse a static analysis tool to check for time manipulation vulnerabilities.
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