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Use Case

Check that the implementation of a contract does not change. This works similarly when checking if the owner of a contract has changed.

This assertions is useful if you want to make sure that a contract is not unexpectedly upgraded or changed to an undesired implementation. For example it would be possible to define a list of allowed implementations that would be whitelisted and any other implementation would be considered an invalid state.

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Explanation

The assertion checks if the address of a contract has changed after a transaction has been executed.

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Code Example

// SPDX-License-Identifier: MIT
pragma solidity 0.8.28;

import {Assertion} from "../lib/credible-std/Assertion.sol";

interface IImplementation {
    function implementation() external view returns (address);
}

contract ImplementationChange is Assertion {
    IImplementation public implementation = IImplementation(address(0xbeef));

    function fnSelectors() external pure override returns (Trigger[] memory) {
        Trigger[] memory triggers = new Trigger[](1); // Define the number of triggers
        triggers[0] = Trigger(TriggerType.STORAGE, this.implementationChange.selector); // Define the trigger
        return triggers;
    }

    // Asssert that the implementation contract address doesn't change
    // during the state transition
    function implementationChange() external returns (bool) {
        ph.forkPreState();
        address preImpl = implementation.implementation();
        ph.forkPostState();
        address postImpl = implementation.implementation();
        return preImpl == postImpl;
    }
}
PhEVM PrecompilesOwner Change