createFork
Signature
function createFork(string calldata urlOrAlias) external returns (uint256)
function createFork(string calldata urlOrAlias, uint256 block) external returns (uint256);
Description
Creates a new fork from the given endpoint and returns the identifier of the fork. If a block number is passed as an argument, the fork will begin on that block, otherwise it will begin on the latest block.
Examples
Create a new mainnet fork with the latest block number:
uint256 forkId = vm.createFork(MAINNET_RPC_URL);
vm.selectFork(forkId);
assertEq(block.number, 15_171_037); // as of time of writing, 2022-07-19 04:55:27 UTC
Create a new mainnet fork with a given block number:
uint256 forkId = vm.createFork(MAINNET_RPC_URL, 1_337_000);
vm.selectFork(forkId);
assertEq(block.number, 1_337_000);