How to access address mapping to array struct in hardhat solidity?

Question

I'm writing Unit Test using hardhat for a solidity contract. There is a public mapping variable which has a mapping of address to array of struct.

 struct ticket {
        uint16 looteryID;
        uint ticketPrice;
        uint ticketSerialNo;
    }

mapping(address => ticket[]) public activeTickets;

function buyLottery(uint16 _id) payable public {
    activeTickets[msg.sender].push(ticket(_id,10,100));
}

I want to write unit test where I want to check the length of ticket array in activeTickets for msg.sender (anyone who is calling buyLottery function). I tried few hit and trail but all failed. Below is one of the attempts which failed.

Unit Test Code

 it("User can buy lottery",async () => { 
await lotteryInstance.connect(addr1).buyLottery(1,{value: ethers.utils.parseEther('1')});
        const userTickets = await lotteryInstance.activeTickets(addr1.address);
             expect(userTickets.length).equal(1);
             expect(userTickets[0].looteryID).equal(1);
            });

This will push and ticket details to activeTickets. If we assume msg.sender is 0xFe123d4 then activeTickets should have something like 0xFe123d4 => [{1,10,100}] Now I want to test whether activeTickets was successfully updated or not, by checking current length of ticket w.r.t address 0xFe123d4 and also by accessing and comparing the pushed value.

Answer 1

Try this way:

 struct ticket {
        uint16 looteryID;
        uint ticketPrice;
        uint ticketSerialNo;
    }

mapping(address => ticket[]) public activeTickets;

function buyLottery(uint16 _id) payable public {
    activeTickets[msg.sender].push(ticket(_id,10,100));
}

function getLooteryID(uint256 index, address userAddress) external view returns(uint16) { 
   return activeTickets[userAddress][index].looteryID;
}

function getLength(address userAddress) external view returns(uint256) {
    return return activeTickets[userAddress].length;
}

and in the test file:

 it("User can buy lottery",async () => { 
const lotteryConnectedToSigner = await lotteryInstance.connect(addr1)
await lotteryConnectedToSigner.buyLottery(1,{value: ethers.utils.parseEther('1')});
const userTickets = await lotteryConnectedToSigner.getLooteryID(0,addr1.address);
const length = lotteryConnectedToSigner.getLength(addr1.address)
             expect(length).equal(1);
             expect(userTickets[0].looteryID).equal(1);
            });

Also you can get all of mapping data using one function and get details after calling function, here to simplify i prefer using 2 separate functions to get looteryID and length.