Foundry Book

`getCode`

Signature

function getCode(string calldata) external returns (bytes memory);

Description

Returns the creation bytecode for a contract in the project given the path to the contract.

The calldata parameter can either be in the form ContractFile.sol (if the filename and contract name are the same), ContractFile.sol:ContractName, or the path to an artifact, relative to the root of your project.

ℹ️ Note

getCode requires read permission for the output directory, see file cheatcodes.

To grant read access set fs_permissions = [{ access = "read", path = "./out"}] in your foundry.toml.

Examples

MyContract myContract = new MyContract(arg1, arg2);

// Let's do the same thing with `getCode`
bytes memory args = abi.encode(arg1, arg2);
bytes memory bytecode = abi.encodePacked(vm.getCode("MyContract.sol:MyContract"), args);
address anotherAddress;
assembly {
    anotherAddress := create(0, add(bytecode, 0x20), mload(bytecode))
}

assertEq0(address(myContract).code, anotherAddress.code); // [PASS]

Deploy a contract to an arbitrary address by combining getCode and etch

// Deploy
bytes memory args = abi.encode(arg1, arg2);
bytes memory bytecode = abi.encodePacked(vm.getCode("MyContract.sol:MyContract"), args);
address deployed;
assembly {
    deployed := create(0, add(bytecode, 0x20), mload(bytecode))
}

// Set the bytecode of an arbitrary address
vm.etch(targetAddr, deployed.code);

Supported formats

You can fetch artifacts by either contract path or contract name. Fetching artifacts for a specific version is also supported. If not provided, cheatcode will default to the version of a test being executed or the only version artifact was compiled with.

vm.getCode("MyContract.sol:MyContract");
vm.getCode("MyContract");
vm.getCode("MyContract.sol:0.8.18");
vm.getCode("MyContract:0.8.18");