Trying to test a simple contract but failing

Question

I am currently following my first Ethereum course, and I am trying to test the a very simple contract, but it keeps failing. When I run the contract on Remix, everything seems to be working fine, so I'm assuming it's the test setup. I would appreciate any input.

The contract:

pragma solidity ^0.4.17;

contract Loaner {
    address public lender;
    address public borrower;
    
    function Lottery() public {}

    function setLender() public {
        lender = msg.sender;
    }

    function setBorrower() public {
        borrower = msg.sender;
    }
}

My test code:

const assert = require('assert');
const ganache = require('ganache-cli');
const Web3 = require('web3');
const web3 = new Web3(ganache.provider());

const { interface, bytecode } = require('../compile');

let loaner;
let accounts;

before(async () => {
    accounts = await web3.eth.getAccounts();
    loaner = await new web3.eth.Contract(JSON.parse(interface))
    .deploy({ data: bytecode })
    .send({ from: accounts[0], gas: '1000000' });
})

describe('Loaner', () => {
    it('deploys a contract', () => {
        assert.ok(loaner.options.address);
    });

    it('allows setting a lender', async () => {
        await loaner.methods.setLender().call({ from: accounts[0] });
        const lender = await loaner.methods.lender().call({ from: accounts[0] });
        assert.equal(lender, accounts[0]);
    });

    it('allows setting a borrower', async () => {
        await loaner.methods.setBorrower().call({ from: accounts[0] });
        const borrower = await loaner.methods.lender().call({ from: accounts[0] });
        assert.equal(borrower, accounts[0]);
    });
})

Results:

Loaner
    ✔ deploys a contract
    1) allows setting a lender
    2) allows setting a borrower


  1 passing (108ms)
  2 failing

  1) Loaner
       allows setting a lender:

      AssertionError [ERR_ASSERTION]: '0x0000000000000000000000000000000000000000' == '0xA441ACf8c2f84D3A4cBb53c0c07f935ee7cc271C'
      + expected - actual

      -0x0000000000000000000000000000000000000000
      +0xA441ACf8c2f84D3A4cBb53c0c07f935ee7cc271C
      
      at Context.<anonymous> (test/Lonaer.test.js:26:16)
      at processTicksAndRejections (node:internal/process/task_queues:94:5)

  2) Loaner
       allows setting a borrower:

      AssertionError [ERR_ASSERTION]: '0x0000000000000000000000000000000000000000' == '0xA441ACf8c2f84D3A4cBb53c0c07f935ee7cc271C'
      + expected - actual

      -0x0000000000000000000000000000000000000000
      +0xA441ACf8c2f84D3A4cBb53c0c07f935ee7cc271C
      
      at Context.<anonymous> (test/Lonaer.test.js:32:16)
      at processTicksAndRejections (node:internal/process/task_queues:94:5)

Answer 1

You are mistaken between call and send. check this (old article but shows the difference) https://bitsofco.de/calling-smart-contract-functions-using-web3-js-call-vs-send/

And this is helpful too https://web3js.readthedocs.io/en/v1.2.11/web3-eth-contract.html#web3-eth-contract

When you are changing the state of the contract like in the method setXXX(..) then you need to send a transaction and use send

Probably this will fix it:

    it('allows setting a lender', async () => {
        await loaner.methods.setLender().send({ from: accounts[0] });
        // wait until the tx is mined then
        const lender = await loaner.methods.lender().call({ from: accounts[0] });
        assert.equal(lender, accounts[0]);
    });

    it('allows setting a borrower', async () => {
        await loaner.methods.setBorrower().send({ from: accounts[0] });
        // wait until the tx is mined then
        const borrower = await loaner.methods.lender().call({ from: accounts[0] });
        assert.equal(borrower, accounts[0]);
    });