Foundry Book

Cheatcodes Reference

Cheatcodes give you powerful assertions, the ability to alter the state of the EVM, mock data, and more.

Cheatcodes are made available through use of the cheatcode address (0x7109709ECfa91a80626fF3989D68f67F5b1DD12D).

ℹ️ Note

If you encounter errors for this address when using fuzzed addresses in your tests, you may wish to exclude it from your fuzz tests by using the following line:

vm.assume(address_ != 0x7109709ECfa91a80626fF3989D68f67F5b1DD12D);

You can also access cheatcodes easily via vm available in Forge Standard Library's Test contract.

Forge Standard Library Cheatcodes

Forge Std implements wrappers around cheatcodes, which combine multiple standard cheatcodes to improve development experience. These are not technically cheatcodes, but rather compositions of Forge's cheatcodes.

You can view the list of Forge Standard Library's cheatcode wrappers in the references section. You can reference the Forge Std source code to learn more about how the wrappers work under the hood.

Cheatcode Types

Below are some subsections for the different Forge cheatcodes.

• Environment: Cheatcodes that alter the state of the EVM.
• Assertions: Cheatcodes that are powerful assertions
• Fuzzer: Cheatcodes that configure the fuzzer
• External: Cheatcodes that interact with external state (files, commands, ...)
• Utilities: Smaller utility cheatcodes
• Forking: Forking mode cheatcodes
• Snapshots: Snapshot cheatcodes
• RPC: RPC related cheatcodes
• File: Cheatcodes for working with files

Add a new cheatcode

If you need a new feature, consider contributing to the Foundry's codebase to add the cheatcode.

Cheatcodes Interface

This is a Solidity interface for all of the cheatcodes present in Forge.

interface CheatCodes {
    // This allows us to getRecordedLogs()
    struct Log {
        bytes32[] topics;
        bytes data;
    }

    // Possible caller modes for readCallers()
    enum CallerMode {
        None,
        Broadcast,
        RecurrentBroadcast,
        Prank,
        RecurrentPrank
    }

    // Set block.timestamp
    function warp(uint256) external;

    // Set block.number
    function roll(uint256) external;

    // Set block.basefee
    function fee(uint256) external;

    // Set block.difficulty
    // Does not work from the Paris hard fork and onwards, and will revert instead.
    function difficulty(uint256) external;
    
    // Set block.prevrandao
    // Does not work before the Paris hard fork, and will revert instead.
    function prevrandao(bytes32) external;

    // Set block.chainid
    function chainId(uint256) external;

    // Loads a storage slot from an address
    function load(address account, bytes32 slot) external returns (bytes32);

    // Stores a value to an address' storage slot
    function store(address account, bytes32 slot, bytes32 value) external;

    // Signs data
    function sign(uint256 privateKey, bytes32 digest)
        external
        returns (uint8 v, bytes32 r, bytes32 s);

    // Computes address for a given private key
    function addr(uint256 privateKey) external returns (address);

    // Derive a private key from a provided mnemonic string,
    // or mnemonic file path, at the derivation path m/44'/60'/0'/0/{index}.
    function deriveKey(string calldata, uint32) external returns (uint256);
    // Derive a private key from a provided mnemonic string, or mnemonic file path,
    // at the derivation path {path}{index}
    function deriveKey(string calldata, string calldata, uint32) external returns (uint256);

    // Gets the nonce of an account
    function getNonce(address account) external returns (uint64);

    // Sets the nonce of an account
    // The new nonce must be higher than the current nonce of the account
    function setNonce(address account, uint64 nonce) external;

    // Performs a foreign function call via terminal
    function ffi(string[] calldata) external returns (bytes memory);

    // Set environment variables, (name, value)
    function setEnv(string calldata, string calldata) external;

    // Read environment variables, (name) => (value)
    function envBool(string calldata) external returns (bool);
    function envUint(string calldata) external returns (uint256);
    function envInt(string calldata) external returns (int256);
    function envAddress(string calldata) external returns (address);
    function envBytes32(string calldata) external returns (bytes32);
    function envString(string calldata) external returns (string memory);
    function envBytes(string calldata) external returns (bytes memory);

    // Read environment variables as arrays, (name, delim) => (value[])
    function envBool(string calldata, string calldata)
        external
        returns (bool[] memory);
    function envUint(string calldata, string calldata)
        external
        returns (uint256[] memory);
    function envInt(string calldata, string calldata)
        external
        returns (int256[] memory);
    function envAddress(string calldata, string calldata)
        external
        returns (address[] memory);
    function envBytes32(string calldata, string calldata)
        external
        returns (bytes32[] memory);
    function envString(string calldata, string calldata)
        external
        returns (string[] memory);
    function envBytes(string calldata, string calldata)
        external
        returns (bytes[] memory);

    // Read environment variables with default value, (name, value) => (value)
    function envOr(string calldata, bool) external returns (bool);
    function envOr(string calldata, uint256) external returns (uint256);
    function envOr(string calldata, int256) external returns (int256);
    function envOr(string calldata, address) external returns (address);
    function envOr(string calldata, bytes32) external returns (bytes32);
    function envOr(string calldata, string calldata) external returns (string memory);
    function envOr(string calldata, bytes calldata) external returns (bytes memory);
    
    // Read environment variables as arrays with default value, (name, value[]) => (value[])
    function envOr(string calldata, string calldata, bool[] calldata) external returns (bool[] memory);
    function envOr(string calldata, string calldata, uint256[] calldata) external returns (uint256[] memory);
    function envOr(string calldata, string calldata, int256[] calldata) external returns (int256[] memory);
    function envOr(string calldata, string calldata, address[] calldata) external returns (address[] memory);
    function envOr(string calldata, string calldata, bytes32[] calldata) external returns (bytes32[] memory);
    function envOr(string calldata, string calldata, string[] calldata) external returns (string[] memory);
    function envOr(string calldata, string calldata, bytes[] calldata) external returns (bytes[] memory);

    // Convert Solidity types to strings
    function toString(address) external returns(string memory);
    function toString(bytes calldata) external returns(string memory);
    function toString(bytes32) external returns(string memory);
    function toString(bool) external returns(string memory);
    function toString(uint256) external returns(string memory);
    function toString(int256) external returns(string memory);

    // Sets the *next* call's msg.sender to be the input address
    function prank(address) external;

    // Sets all subsequent calls' msg.sender to be the input address
    // until `stopPrank` is called
    function startPrank(address) external;

    // Sets the *next* call's msg.sender to be the input address,
    // and the tx.origin to be the second input
    function prank(address, address) external;

    // Sets all subsequent calls' msg.sender to be the input address until
    // `stopPrank` is called, and the tx.origin to be the second input
    function startPrank(address, address) external;

    // Resets subsequent calls' msg.sender to be `address(this)`
    function stopPrank() external;

    // Reads the current `msg.sender` and `tx.origin` from state and reports if there is any active caller modification
    function readCallers() external returns (CallerMode callerMode, address msgSender, address txOrigin);

    // Sets an address' balance
    function deal(address who, uint256 newBalance) external;

    // Set the balance of an account for any ERC20 token
    function deal(address token, address to, uint256 give) external;
    
    // Alternative signature to update `totalSupply`
    function deal(address token, address to, uint256 give, bool adjust) external;
    
    // Sets an address' code
    function etch(address who, bytes calldata code) external;

    // Expects an error on next call
    function expectRevert() external;
    function expectRevert(bytes calldata) external;
    function expectRevert(bytes4) external;

    // Record all storage reads and writes
    function record() external;

    // Gets all accessed reads and write slot from a recording session,
    // for a given address
    function accesses(address)
        external
        returns (bytes32[] memory reads, bytes32[] memory writes);

    // Record all the transaction logs
    function recordLogs() external;

    // Gets all the recorded logs
    function getRecordedLogs() external returns (Log[] memory);

    // Prepare an expected log with the signature:
    //   (bool checkTopic1, bool checkTopic2, bool checkTopic3, bool checkData).
    //
    // Call this function, then emit an event, then call a function.
    // Internally after the call, we check if logs were emitted in the expected order
    // with the expected topics and data (as specified by the booleans)
    //
    // The second form also checks supplied address against emitting contract.
    function expectEmit(bool, bool, bool, bool) external;
    function expectEmit(bool, bool, bool, bool, address) external;

    // Mocks a call to an address, returning specified data.
    //
    // Calldata can either be strict or a partial match, e.g. if you only
    // pass a Solidity selector to the expected calldata, then the entire Solidity
    // function will be mocked.
    function mockCall(address, bytes calldata, bytes calldata) external;

    // Reverts a call to an address, returning the specified error
    //
    // Calldata can either be strict or a partial match, e.g. if you only
    // pass a Solidity selector to the expected calldata, then the entire Solidity
    // function will be mocked.
    function mockCallRevert(address where, bytes calldata data, bytes calldata retdata) external;

    // Clears all mocked and reverted mocked calls
    function clearMockedCalls() external;

    // Expect a call to an address with the specified calldata.
    // Calldata can either be strict or a partial match
    function expectCall(address, bytes calldata) external;
    // Expect a call to an address with the specified
    // calldata and message value.
    // Calldata can either be strict or a partial match
    function expectCall(address, uint256, bytes calldata) external;

    // Gets the _creation_ bytecode from an artifact file. Takes in the relative path to the json file
    function getCode(string calldata) external returns (bytes memory);
    // Gets the _deployed_ bytecode from an artifact file. Takes in the relative path to the json file
    function getDeployedCode(string calldata) external returns (bytes memory);

    // Label an address in test traces
    function label(address addr, string calldata label) external;
    
    // Retrieve the label of an address
    function getLabel(address addr) external returns (string memory);

    // When fuzzing, generate new inputs if conditional not met
    function assume(bool) external;

    // Set block.coinbase (who)
    function coinbase(address) external;

    // Using the address that calls the test contract or the address provided
    // as the sender, has the next call (at this call depth only) create a
    // transaction that can later be signed and sent onchain
    function broadcast() external;
    function broadcast(address) external;

    // Using the address that calls the test contract or the address provided
    // as the sender, has all subsequent calls (at this call depth only) create
    // transactions that can later be signed and sent onchain
    function startBroadcast() external;
    function startBroadcast(address) external;

    // Stops collecting onchain transactions
    function stopBroadcast() external;

    // Reads the entire content of file to string, (path) => (data)
    function readFile(string calldata) external returns (string memory);
    // Get the path of the current project root
    function projectRoot() external returns (string memory);
    // Reads next line of file to string, (path) => (line)
    function readLine(string calldata) external returns (string memory);
    // Writes data to file, creating a file if it does not exist, and entirely replacing its contents if it does.
    // (path, data) => ()
    function writeFile(string calldata, string calldata) external;
    // Writes line to file, creating a file if it does not exist.
    // (path, data) => ()
    function writeLine(string calldata, string calldata) external;
    // Closes file for reading, resetting the offset and allowing to read it from beginning with readLine.
    // (path) => ()
    function closeFile(string calldata) external;
    // Removes file. This cheatcode will revert in the following situations, but is not limited to just these cases:
    // - Path points to a directory.
    // - The file doesn't exist.
    // - The user lacks permissions to remove the file.
    // (path) => ()
    function removeFile(string calldata) external;
    
    // Return the value(s) that correspond to 'key'
    function parseJson(string memory json, string memory key) external returns (bytes memory);
    // Return the entire json file
    function parseJson(string memory json) external returns (bytes memory);

    // Snapshot the current state of the evm.
    // Returns the id of the snapshot that was created.
    // To revert a snapshot use `revertTo`
    function snapshot() external returns (uint256);
    // Revert the state of the evm to a previous snapshot
    // Takes the snapshot id to revert to.
    // This deletes the snapshot and all snapshots taken after the given snapshot id.
    function revertTo(uint256) external returns (bool);

    // Creates a new fork with the given endpoint and block,
    // and returns the identifier of the fork
    function createFork(string calldata, uint256) external returns (uint256);
    // Creates a new fork with the given endpoint and the _latest_ block,
    // and returns the identifier of the fork
    function createFork(string calldata) external returns (uint256);

    // Creates _and_ also selects a new fork with the given endpoint and block,
    // and returns the identifier of the fork
    function createSelectFork(string calldata, uint256)
        external
        returns (uint256);
    // Creates _and_ also selects a new fork with the given endpoint and the
    // latest block and returns the identifier of the fork
    function createSelectFork(string calldata) external returns (uint256);

    // Takes a fork identifier created by `createFork` and
    // sets the corresponding forked state as active.
    function selectFork(uint256) external;

    // Returns the currently active fork
    // Reverts if no fork is currently active
    function activeFork() external returns (uint256);

    // Updates the currently active fork to given block number
    // This is similar to `roll` but for the currently active fork
    function rollFork(uint256) external;
    // Updates the given fork to given block number
    function rollFork(uint256 forkId, uint256 blockNumber) external;

    // Fetches the given transaction from the active fork and executes it on the current state
    function transact(bytes32) external;
    // Fetches the given transaction from the given fork and executes it on the current state
    function transact(uint256, bytes32) external;

    // Marks that the account(s) should use persistent storage across
    // fork swaps in a multifork setup, meaning, changes made to the state
    // of this account will be kept when switching forks
    function makePersistent(address) external;
    function makePersistent(address, address) external;
    function makePersistent(address, address, address) external;
    function makePersistent(address[] calldata) external;
    // Revokes persistent status from the address, previously added via `makePersistent`
    function revokePersistent(address) external;
    function revokePersistent(address[] calldata) external;
    // Returns true if the account is marked as persistent
    function isPersistent(address) external returns (bool);

    /// Returns the RPC url for the given alias
    function rpcUrl(string calldata) external returns (string memory);
    /// Returns all rpc urls and their aliases `[alias, url][]`
    function rpcUrls() external returns (string[2][] memory);
}