--- ### Setting Up the Halmos Test Environment First, let’s navigate to our working directory named “invariant break formal verification” and begin by creating a new file titled `HalmoseTest.t.sol`. This file will contain all the code required for using Halmos to formally verify the robustness of our code. ### Writing the Code We'll start by importing necessary components. First, integrate the standard test contract from `forge-std` by adding: ```solidity import {Test} from "forge-std/Test.sol"; ``` Next, we need to bring in the specific contract we wish to verify, named `formalVerificationCatches.sol`, which is located in a nested directory structure: ```solidity import {FormalVerificationCatches} "../../../src/invariant-break/FormalVerificationCatches.sol"; ``` ### Initializing the Verification Contract Create a setup function within your `HalmosTest` contract to deploy the verification contract, like so: ```solidity function setup() public { fvc = new formalVerificationCatches(); } ``` ### Writing the Test Function In Halmos, assertions are key, with the tool focusing entirely on these statements to conduct verification. Therefore, structure your test to include necessary assertions: ```solidity function testHellFuncDoesntRevert(uint128 num) public { (bool success, ) = address(FVC).staticcall(abi.encodeWithSelector(FVC.hellFunc.selector, num)); assert(success); } ``` ### Setting Up Halmos To utilize Halmos, ensure you have Python installed as it is required for the installation. If you haven’t installed Python yet, this would be a good starting point. Once Python is ready, install Halmos using pip: ```bash pip install halmos ``` Alternatively, for a more isolated setup, consider using Pipx to install Halmos: ```bash pipx install halmos ``` ### Running the Halmos Test Once everything is set up, you can execute the Halmos command on the test, which is designed to simulate and verify the function without causing reverts. This process converts the function into a mathematical expression and seeks to prove or disprove the specified conditions: ```bash halmos test HalmosTest.sol ``` ### Reviewing the Output and Adjustments After running the test, Halmos might provide insights such as counterexamples where the function might fail. These can be used to refine the tests or understand better where the code might not meet the desired conditions. ```bash forge test --mt ``` ### Conclusion This guide should help you set up and run a basic Halmos test, illustrating the transition from Foundry-based tests to formal verification using Halmos. As with any tool, familiarity will grow with use, helping to uncover more about its capabilities and limitations.