fuzz doesn't catch my invariant check

[iftikharuddin]

This is my StatelessFuzzCatches contract, where i set a condition that if myNumber == 40 it should return zero.

// SPDX-License-Identifier: MIT
pragma solidity 0.8.20;

// INVARIANT: doMath should never return 0
contract StatelessFuzzCatches {
    /*
     * @dev Should never return 0
     */
    function doMath(uint128 myNumber) public pure returns (uint256) {
        if (myNumber == 40) {
            return 0;
        }
        return 1;
    }
}

Here is the Stateless Fuzz test i wrote:

// SPDX-License-Identifier: MIT
pragma solidity 0.8.20;

import {Test} from "forge-std/Test.sol";
import {StatelessFuzzCatches} from "../../src/invariant-break/StatelessFuzzCatches.sol";

contract StatelessFuzzCatchesTest is Test {
    StatelessFuzzCatches public sfc;

    function setUp() public {
        sfc = new StatelessFuzzCatches();
    }

     // Stateless fuzz
     function testFuzzCatchesBugStateless(uint128 randomNumber) public view {
         assert(sfc.doMath(randomNumber) != 0);
     }
}

When I run the test forge test --match-test testFuzzCatchesBugStateless the result is below:

[PASS] testFuzzCatchesBugStateless(uint128) (runs: 1000, μ: 5717, ~: 5717)
Test result: ok. 1 passed; 0 failed; 0 skipped; finished in 67.28ms
 
Ran 1 test suites: 1 tests passed, 0 failed, 0 skipped (1 total tests)

Why it didn't catch the randomNumber == 40 check? Should I increase the number of runs or am i doing anything incorrect.

[Chinwuba22]

I think fail_on_revert was either not added or was set/defaulted to false. You can add/change this by adding fail_on_revert = true under the fuzz/invariant section in your toml file.

[cromewar]

@iftikharuddin does this make sense to you?

[iftikharuddin]

Hey

Thanks for answering, I just changed fail_on_revert = true but still same results

Contract:

Test:

[iftikharuddin]

Ok so I just changed runs = 10000 and it worked :) Thanks guys 🙏