Clarification on Using VRFCoordinatorV2_5 vs. VRFCoordinatorV2_5Mock for Creating Subscriptions Programmatically

[YusufsDesigns]

Question

I am working on the decentralized lottery smart contract project that requires creating a Chainlink VRF subscription programmatically. Below is an excerpt of my implementation:

Code Snippet

function createSubscription(address vrfCoordinator) public returns (uint256, address) {
    console2.log("Creating subscription on chain Id: ", block.chainid);
    vm.startBroadcast();
    uint256 subId = VRFCoordinatorV2_5Mock(vrfCoordinator).createSubscription();
    vm.stopBroadcast();
    console2.log("Your subscription Id is: ", subId);
    console2.log("Please update the subscription Id in your HelperConfig.s.sol");
    return (subId, vrfCoordinator);
}

---

My Questions

1. Should I use VRFCoordinatorV2_5(vrfCoordinator) instead of VRFCoordinatorV2_5Mock(vrfCoordinator) when deploying to a live network (e.g., mainnet or testnet)?

   • I understand that the mock is ideal for local development and testing. However, for creating an actual subscription on-chain, it seems I should use the real VRFCoordinatorV2_5. Could you confirm this understanding?

2. Is it possible to dynamically handle the switch between the mock and the real VRFCoordinator using my HelperConfig setup?

   • The HelperConfig is designed to provide the correct VRFCoordinator address based on the chain ID. Would this approach suffice for seamless transitions between local testing and live deployments?

3. Best Practices for Managing Helper Configurations

   • If I need to programmatically fund the subscription and add a consumer using the real VRFCoordinatorV2_5, are there any specific nuances or gotchas I should be aware of?

I would appreciate any insights or recommendations for improving my implementation to handle subscriptions dynamically and effectively across different environments.

Thank you!

[EngrPips]

Hey @YusufsDesigns, The main essence of Patrick writing a HelperConfig in the course was to make it clear that we can easily have a modular deployment and script running process. So yes, with your HelperConfig, you can easily make the running process different for every single chain that exists out there, whether local or live or test.

So for the VRFCoordinatorV2_5(vrfCoordinator) / VRFCoordinatorV2_5Mock(vrfCoordinator), you can use either of them since they boil down to the same signature for the call you want to make and at the end of the day the same calldata will be produced by either of them, but if there were to be a discrepancy in the methods, then you would have to use the correct interface for any chain you are running on.

Please ask questions if anything is confusing.

[YusufsDesigns]

Thank very much, I understand it now.

[EngrPips]

Awesome, I am glad you understood it.