Testing ChainlinkClient callbacks - how to bypass recordChainlinkFulfillment? - testing

Question

I've got a Chainlink client contract which makes a DirectRequest to an oracle. The oracle does its thing and then returns the answer via the typical callback selector passed in via the ChainlinkRequest. It all works well, but I'd like to write some tests that test the callback implementation
My client contract is as follows:
contract PriceFeed is Ownable, ChainlinkClient {
function updatePrice() onlyOwner returns (bytes32 requestId) {
// makes Chainlink request specifying callback via this.requestCallback.selector
}
function requestCallback(bytes32 _requestId, uint256 _newPrice) public
recordChainlinkFulfillment(_requestId) {
price = _newPrice;
}
}
The problem arises when the test code calls requestCallback(...) and the code hits the recordChainlinkFulfillment(...) modifier. The ChainlinkClient complains that the requestId being passed in by the test below isn't in the underling private pendingRequests mapping maintained by the ChainlinkClient.
The simplified version of ChainlinkClient looks like this:
contract ChainlinkClient {
mapping(bytes32 => address) private pendingRequests;
modifier recordChainlinkFulfillment(bytes32 _requestId) {
require(msg.sender == pendingRequests[_requestId], "Source must be the oracle of the request");
delete pendingRequests[_requestId];
emit ChainlinkFulfilled(_requestId);
_;
}
}
My Foundry/Solidity test is as follows:
contract PriceFeedTest is Test {
function testInitialCallback() public {
priceFeed.requestCallback("abc123", 1000000); // fails on this line
assertEq(1000000, priceFeed.price(), "Expecting price to be 1000000");
}
}
The code fails on first line of the testInitialCallback() line with: Source must be the oracle of the request
How can I trick the ChainklinkClient into allowing my callback to get past the modifier check? AFAIK I can't access and pre-populate the private pendingRequests mapping. Is there another way?
I know that Foundry provides Cheatcodes to help in testing and there's a stdstorage cheatcode, but I'm not familiar on how to construct a call to stdstorage to override pendingRequests if thats even possible with a cheatcode.
contract PriceFeedTest is Test {
function testInitialCallback2() public {
stdstore
.target(address(priceFeed))
.sig("pendingRequests()")
.with_key("abc123")
.checked_write(address(this));
priceFeed.requestCallback("abc123", 1000000);
assertEq(1000000, priceFeed.price(), "Expecting price to be 1000000");
}
}
The above code throws the following error: No storage use detected for target
Any help would be greatly appreciated. Many thanks.

Answer 1

When you execute the updatePrice function in your test, you should be able to strip out the requestId from the transaction receipt event. Once you have that, you can then use it in your call to requestCallback. Check out this example unit test from the hardhat starter kit for an example of this