How to fork a deployed smart contract on mainnet and redeploy it on testnet?

Question

I am building a contract which integrates with an existing contract on mainnet.

1. Are there any tools I can use to test my integration with this contract without spending real gas? Or is there an easy way to fork the contract and redeploy it on testnet? I'm not sure how to copy all the solidity code on etherscan as there are many dependencies, especially since it is a proxy contract.

2. I understand that one way of interacting with an external contract within a contract, is to import the object from the solidity code. However, do I always need to import the full contract object from the solidity code, or is it possible to achieve the same thing just with the ABI?

Answer 1

1. I think the best way forward would be to fork mainnet into your local environment, I've tested with hardhat and foundry and is quite straight forward, you can see the hardaht docs here https://hardhat.org/hardhat-network/docs/guides/forking-other-networks

2. Actually you could instantiate the contract with the method you require. Imagine you want to call the transfer method from a ERC20 contract. Then you could create the interface like:

   interface IERC20 { function transfer(address to, uint256 amount) external; }

and then in your code:

IERC20(token address).transfer(to,amount);

Hope it helps