How to test the revert for 'call' function with Hardhat?

Question

I would like to have 100% code coverage but one function is giving trouble ...

(bool sent, bytes memory data) = _to.call{value: msg.value}("");
require(sent, "Failed to send Ether");

How to force the boolean 'sent' to false ?

Stack : hardhat, solidity, ethers.js, chai.js

I tried to modify the balance of the address which must pay :

await network.provider.send("hardhat_setBalance", [
 "...address...",
 "0x1000"
]);

But i don't go to the require, i've got this error :

sender doesn't have enough funds to send tx

Any idea please ?

Answer 1

(bool sent, bytes memory data) = _to.call{value: msg.value}("");

How to force the boolean 'sent' to false ?

The first value becomes false when the transfer fails.

For example when the recipient is a contract that doesn't implement the receive() nor fallback() special functions.

So you can have a mock contract that always rejects all native transfers, and assign it as the to address.

pragma solidity 0.8.20;

contract FailingRecipient {}