ERC4337 Validation is a Solidity library that can be installed in different ways. Below, you will find instructions for using it together with Foundry.

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Installation

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Using a package manager

npm i @rhinestone/erc4337-validation

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Using git submodules

forge install rhinestonewtf/erc4337-validation

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Quick Start

To use this library, simply import the Simulator and set it up as follows: 
import {Simulator} from "@rhinestone/erc4337-validation/Simulator.sol";

contract Example {
    using Simulator for PackedUserOperation; // or UserOperation

   function verify(PackedUserOperation memory userOp) external view {
        // Verify the ERC-4337 rules
        userOp.simulateUserOp(entryPointAddress);
    }
}
If the userOp breaks any of the rules, the function will revert with a message indicating which rule was broken. Note that the entryPointAddress needs to be the address of the EntryPointSimulations contract if you are using v0.7 of ERC-4337. For an example see the Simulator test, the Simulator test v0.6 and the relevant test bases.