MultiversX Property Testing

This skill guides you in using property-based testing (fuzzing) to find edge cases in Smart Contract logic.

1. Tools

• cargo fuzz: Standard Rust fuzzer.
• proptest: Property testing framework for Rust.

2. Methodology

Defining Invariants:

• "Total Supply MUST equal sum of all balances."
• "User balance MUST NOT decrease if deposit fails."

3. Implementation (RustVM)

Write a test that:

1. Takes random input (random amounts, random user IDs).
2. Executes the contract logic via blockchain_mock.
3. Asserts the invariant holds.

4. Example

proptest! {
    #[test]
    fn test_deposit_always_increases_balance(amount in 0u64..1_000_000u64) {
        let mut setup = Setup::new();
        setup.deposit(amount);
        assert_eq!(setup.balance(), amount);
    }
}