sender doesn't seem to be forwarded in MulticallerWithSender forge test

[stephankmin]

I'm working on a router contract that calls MulticallerWithSender in order to "forward" the router's address as msg.sender.

I set up a test to call transfer on an ERC20 to transfer tokens from the router to bob. But I'm seeing an error that the MulticallerWithSender contract has insufficient balance.

For context, I am using a batch permit2 signature then calling aggregateWithSender:

function permitMulticallWithSender(
        address user,
        ISignatureTransfer.PermitBatchTransferFrom memory permit,
        address[] calldata targets,
        bytes[] calldata data,
        uint256[] calldata values,
        bytes memory permitSignature
    ) external {
        if (permitSignature.length != 0) {
            // Use permit to transfer tokens from user to router
            _handlePermitBatch(user, permit, permitSignature);
        }
        // Perform the multicall and refund to the user
        MULTICALLER_WITH_SENDER.aggregateWithSender(targets, data, values);
    }

This is how I'm calling MulticallerEtcher in setUp():

multicaller = MulticallerEtcher.multicaller();
multicallerWithSender = MulticallerEtcher.multicallerWithSender();

Is there any additional setup I need in my test? Any help would be appreciated!