Testing, Debugging, and Auditing Contracts BDC Practice Questions (Page 5)

Questions 21–25

1. 21foundation · easy

   When writing a unit test for a Solidity function that increments a counter, what should the test verify?

   • AThat the counter's value after the call is exactly one more than before the call.
   • BThat the function reverts if the counter is zero.
   • CThat the function returns the address of the contract.
   • DThat the function consumes exactly 100,000 gas.
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2. 22application · medium

   A team is building a DeFi application where a `Router` contract calls a `LiquidityPool` contract to swap tokens. The developer wants to write integration tests that verify the entire swap flow, including the transfer of tokens between the user, the router, and the pool. Which testing setup is most appropriate?

   • ADeploy both contracts in a local test environment and execute a swap with a funded test account, then assert the final token balances.
   • BUse a static analyzer to check that the Router contract has the correct function signatures for the pool.
   • CWrite a unit test for the Router contract that mocks the LiquidityPool contract's return values.
   • DDeploy only the Router contract to a public testnet and call its swap function with a random address.
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4. 23application · medium

   A developer is writing unit tests for a Solidity token contract that has a `transfer` function with a `require(balances[msg.sender] >= amount)` check. The developer wants to verify that the function correctly reverts when the sender has insufficient funds. Which testing approach should the developer use?

   • ACall `transfer` with an amount exceeding the sender's balance and assert that the transaction reverts.
   • BUse a static analysis tool to scan the contract for missing require statements.
   • CCall `transfer` with a valid amount and assert the recipient's balance increases.
   • DDeploy the contract to a testnet and manually send a transaction with insufficient funds.
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5. 24application · medium

   A company is about to launch a DeFi protocol and has hired an external audit firm. The audit firm has completed its review and delivered a report with several findings. What is the next step the company should take before deploying the contract?

   • ADeploy the contract immediately because the audit report is the final approval.
   • BPublish the audit report and ignore the findings because they are only recommendations.
   • CRemediate the findings, re-test the changes, and have the auditor verify the fixes.
   • DRun a static analysis tool once more and then deploy without addressing the findings.
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6. 25foundation · easy

   What is the role of an auditor in a smart contract security audit?

   • ATo guarantee that the contract is 100% secure.
   • BTo deploy the contract to the mainnet.
   • CTo write the smart contract code for the client.
   • DTo identify vulnerabilities and provide recommendations for remediation.
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