Im using a course, and I got this error:

ReferenceError: totalSupply is not defined

and Idk what it means by that, cause I never got this error before. can somebody help me fix this error? thanks and this is my code:

const { assert } = require("chai");

const KryptoBird = artifacts.require("KryptoBird");

// check for chai

contract('KryptoBird', (accounts) => {

    let contract
    before( async () => {
    contract = await KryptoBird.deployed()
    describe('deployment', async() => {
        it("deploys successfully", async () => {
            const address = contract.address;
            assert.notEqual(address, '')
            assert.notEqual(address, null)
            assert.notEqual(address, undefined)
            assert.notEqual(address, 0x0)
        it('has a name', async() => {
            const name = await contract.name()
            assert.equal(name, 'KryptoBird')

        it('has a symbol', async() => {
            const symbol = await contract.symbol()
            assert.equal(symbol, 'KBIRDZ')


    describe('minting', async ()=> {
        it('creates a new token', async ()=> {
            const result = await contract.mint('https...1')
            const totalSupply = await contract.totalSupply();
            assert.equal(totalSupply, 1)
            const event = result.logs[0].args
            assert.equal(event._from, '0x0000000000000000000000000000000000000000', 'from is the contract')
            assert.equal(event._to, accounts[0], 'to is msg.sender')

            await contract.mint('https...1').should.be.rejected

    describe('indexing', async()=> {
        it('lists KryptoBirdz', async()=> {            
        // Mint three new tokens
        await contract.mint('https...2')
        await contract.mint('https...3')
        await contract.mint('https...4')
        const totalSupply = await contract.totalSupply()

        let result = []
        let KryptoBird
        for(i = 1; i <= totalSupply; i++) {
            KryptoBird = await contract.kryptoBirdz(i)

    let expected = ['https...1','https...2','https...3','https...4']
    assert.equal(result.join(','), expected.join(','))



if u need another contract, just tell me, and if u could help me, thanks so much, because I need to finish this today. I've been trying to fix this for 2 hours, it didnt work. so please, if u could help me, it would mean a LOT to me.

here another code:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import './libraries/ERC721.sol';
import './libraries/IERC721Enumerable.sol';

contract ERC721Enumerable is IERC721Enumerable, ERC721 {

    uint256[] private _allTokens;

    // mapping from tokenId to position in _allTokens array
        mapping(uint256 => uint256) private _allTokensIndex;

    // mapping of owner to list of all owner token ids
        mapping(address => uint256[]) private _ownedTokens;

    // mapping from token ID to index of the owner tokens list 
        mapping(uint256 => uint256) private _ownedTokensIndex;

constructor() {

    function _mint(address to, uint256 tokenId) internal override(ERC721) {
        super._mint(to, tokenId);

        _addTokensToOwnerEnumeration(to, tokenId);

    function _addTokensToAllTokenEnumeration(uint256 tokenId) private {
        _allTokensIndex[tokenId] = _allTokens.length;

    function _addTokensToOwnerEnumeration(address to, uint256 tokenId) private {
        _ownedTokensIndex[tokenId] = _ownedTokens[to].length;

    // two functions - one that returns tokenByIndex and 
    // another one that returns tokenOfOwnerByIndex
    function tokenByIndex(uint256 index) public override view returns(uint256) {
        // make sure that the index is not out of bounds of the total supply 
        require(index < totalSupply(), 'global index is out of bounds!');
        return _allTokens[index];

    function tokenOfOwnerByIndex(address owner, uint index) public override view returns(uint256) {
        require(index < balanceOf(owner),'owner index is out of bounds!');
        return _ownedTokens[owner][index];

    // return the total supply of the _allTokens array
    function totalSupply() public override  view returns(uint256) {
        return _allTokens.length;


1 Answer 1


Without your contract code, I can only assume that a possible issue could be your contract inherits from ERC721 instead of ERC721Enumerable, which contains the totalSupply() function, while ERC721 does not.

  • which contract code do u need?
    – Korumaq1xa
    Sep 2, 2022 at 2:40
  • As much as you can provide
    – kev1n
    Sep 2, 2022 at 2:43
  • I sent the ERC721Enumerable code, is that what u need?
    – Korumaq1xa
    Sep 2, 2022 at 2:46
  • No now i'm just confused
    – kev1n
    Sep 2, 2022 at 2:51
  • what contract do u need to be specific? like the name
    – Korumaq1xa
    Sep 2, 2022 at 2:55

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