CBSE Blockchain System Testing 4

Question 1

A QA engineer wants to test that a smart contract's time-lock mechanism cannot be bypassed using block timestamp manipulation. Which test setup is required?

Accepted Answer

Use a local testnet where block timestamps can be manually set to future values

Answer

Deploy on mainnet and wait for the lock period to expire

Answer

Audit the Solidity source code for block.timestamp usage

Answer

Run the contract through a gas estimator

Question 2

Which of the following is the correct test to check for an 'uninitialized storage pointer' vulnerability in a Solidity contract?

Accepted Answer

Deploy the contract and read storage slot 0 before any initialization occurs

Answer

Call the contract constructor twice and observe state

Answer

Fuzz all public functions with zero-value inputs

Answer

Check that all events are emitted in the correct order

Question 3

During a blockchain network partition test, a 5-node PoA network splits into groups of 3 and 2. What is the expected correct behavior?

Accepted Answer

The minority partition (2 nodes) halts; the majority (3 nodes) continues

Answer

Both partitions continue producing blocks independently

Answer

All nodes halt until the partition heals

Answer

The node with the highest block number becomes the authority

Question 4

What does a 'storage collision' test in upgradeable proxy contracts verify?

Accepted Answer

That the proxy and implementation contracts do not declare state variables at the same storage slots

Answer

That the proxy correctly delegates calls to the implementation

Answer

That upgrade operations emit the correct events

Answer

That only the admin can trigger an upgrade

Question 5

A blockchain security tester observes that a contract's fallback function consumes more than 2300 gas. Why is this a security concern in a test report?

Accepted Answer

It prevents the contract from receiving ETH via transfer()/send()

Answer

It allows the contract to call external contracts unexpectedly

Answer

It causes the contract to self-destruct on receive

Answer

It makes the contract incompatible with EIP-1559

Question 6

In a permissioned blockchain (e.g., Hyperledger Fabric), which test validates that endorsement policies are correctly enforced?

Accepted Answer

Submit a transaction endorsed by fewer peers than the policy requires and confirm it is rejected

Answer

Submit a transaction with an invalid chaincode ID and confirm rejection

Answer

Query the ledger state without a valid certificate

Answer

Invoke chaincode from a peer not in the channel

Question 7

What is the main purpose of 'invariant testing' (property-based testing) in smart contract security?

Accepted Answer

To confirm that certain system-wide properties always hold true regardless of the sequence of operations performed

Answer

To verify that gas costs remain constant across contract versions

Answer

To check that all events match the ABI specification

Answer

To validate that contract bytecode matches verified source code