makePersistent

Signature

function makePersistent(address account) external;
function makePersistent(address account0, address account1) external;
function makePersistent(address account0, address account1, address account2) external;
function makePersistent(address[] calldata accounts) external;

Description

Each fork (createFork) has its own independent storage, which is also replaced when another fork is selected (selectFork). By default, only the test contract account and the caller are persistent across forks, which means that changes to the state of the test contract (variables) are preserved when different forks are selected. This way data can be shared by storing it in the contract’s variables.

However, with this cheatcode, it is possible to mark the specified accounts as persistent, which means that their state is available regardless of which fork is currently active.

Examples

Mark a new contract as persistent

contract SimpleStorageContract {
    string public value;

    function set(uint256 _value) public {
        value = _value;
    }
}

function testMarkPersistent() public {
    // by default the `sender` and the contract itself are persistent
    assert(cheats.isPersistent(msg.sender));
    assert(cheats.isPersistent(address(this)));

    // select a specific fork
    cheats.selectFork(mainnetFork);
    
    // create a new contract that's stored in the `mainnetFork` storage
    SimpleStorageContract simple = new SimpleStorageContract();
    
    // `simple` is not marked as persistent
    assert(!cheats.isPersistent(address(simple)));
    
    // contract can be used
    uint256 expectedValue = 99;
    simple.set(expectedValue);
    assertEq(simple.value(), expectedValue);
    
    // mark as persistent
    cheats.makePersistent(address(simple));
    
    // select a different fork
    cheats.selectFork(optimismFork);
    
    // ensure contract is still persistent   
    assert(cheats.isPersistent(address(simple)));
    
    // value is set as expected
    assertEq(simple.value(), expectedValue);
}

SEE ALSO