hardhat test: <functionName> is not a function

Question

i'm testing my contracts on hardhat network with fork of BSC.

i'm deploying my token contract that have mint function:

// @dev Creates `_amount` token to `_to`. Must only be called by the owner (MasterChef).
function mint(address _to, uint256 _amount) public onlyOwner {
    _mint(_to, _amount);
    _moveDelegates(address(0), _delegates[_to], _amount);
}

then i'm deploying it on test using > npx hardhat test , it will run tests of this code:

...
it("Should deploy", async () => {
        token = await Token.deploy();
        await token.deployed();
        console.debug(`\t\t\tToken Contract Address: ${cyan}`, token.address);
        const supply = await token.totalSupply()
        console.debug(`\t\t\tToken totalSupply: ${yellow}`, supply);
        await token.mint(owner.address, web3.utils.toWei("1000", 'ether'))
        console.debug(`\t\t\tToken owner balance: ${cyan}`, token.balanceOf(owner.address));
 });
 ...

test print the first 2 console debug correctly :

 Token Contract Address: 0x5FbDB2315678afecb367f032d93F642f64180aa3
 Token totalSupply: 0

also token.totalSupply() works, so the token is deployed correctly, but when it have to call token.mint() it give this error:

 TypeError: token.mint is not a function
  at Context.<anonymous> (test/general.js:102:21)
  at runMicrotasks (<anonymous>)
  at processTicksAndRejections (internal/process/task_queues.js:95:5)

i tried to clean all the artifacts running > npx hardhat clean and delated all the cache, but i still have the error

Answer 1

if you declared two mint functions then you have to explicitly use the fully qualified signature. Example:

token["mint(address,uint256)"](owner.address, web3.utils.toWei("1000", 'ether'))

I found the solution here https://github.com/ethers-io/ethers.js/issues/407

Answer 2

functionName is not a function this error occurs if the function is not available in your smart contract. in your case the function name is not mint() it's _mint().

Answer 3

in beforeEach() block of code get your contract object by -

const token = await ethers.getContractFactory("Token")

If you haven't defined beforeEach() block define it before it() block

  beforeEach(async function () {
    Token = await ethers.getContractFactory("Token")
    token = await token.deploy()
  })

define Token and token using let keyword before, also somewhere in your code you may be missing await somewhere so that could be also the reason. Thanks.