ERROR processing when testing the contract - TypeError: Cannot read property 'length' of undefined

Question

I am getting the following error while trying to test a FundMe contract.

I am following:

Learn Blockchain, Solidity, and Full Stack Web3 Development with JavaScript – 32-Hour Course by Patrick Collins on FreeCodeCamp YT channel

I got this error while I was at 11:18:00 on the above course. I tried almost everything but nothing helped I found where the problem was.

Question: Where do I find the problem in the test file?

For me, I don't know how to fix it because the error is almost the same question I had when deploying, and I just add a few codes in the hardhat.config.js file. But in the testing, I had the same problem but it doesn't work.

namedAccounts: {
    deployer: {
        default: 0, // here this will by default take the first account as deployer
    },
},

For my FundMe.test.js

const { assert, expect } = require("chai")
const { deployments, network, ethers } = require("hardhat")

describe("FundMe", function () {
    let fundMe
    let mockV3Aggregator
    let deployer
    beforeEach(async () => {
        // const accounts = await ethers.getSigners()
        // deployer = accounts[0]
        deployer = (await getNamedAccounts()).deployer
        await deployments.fixture(["all"])
        fundMe = await ethers.getContract("FundMe", deployer)
        mockV3Aggregator = await ethers.getContract(
            "MockV3Aggregator",
            deployer
        )
    })

    describe("constructor", function () {
        it("sets the aggregator addresses correctly", async () => {
            const response = await fundMe.getPriceFeed()
            assert.equal(response, mockV3Aggregator.address)
        })
    })
})

Here is the error:

  FundMe
    constructor

      1) "before each" hook for "sets the aggregator addresses correctly"


  0 passing (1s)
  1 failing

  1) FundMe
       "before each" hook for "sets the aggregator addresses correctly":
   
   ERROR processing /Users/namnguyen/Workspace/blockchain/smart-contract-programming/hardhat-fund-me/deploy/01-deploy-fund-me.js:
TypeError: Cannot read property 'length' of undefined
    at getFrom (/Users/namnguyen/Workspace/blockchain/smart-contract-programming/hardhat-fund-me/node_modules/hardhat-deploy/src/helpers.ts:1713:14)
    at fetchIfDifferent (/Users/namnguyen/Workspace/blockchain/smart-contract-programming/hardhat-fund-me/node_modules/hardhat-deploy/src/helpers.ts:939:38)
    at processTicksAndRejections (internal/process/task_queues.js:95:5)
    at runNextTicks (internal/process/task_queues.js:64:3)
    at listOnTimeout (internal/timers.js:526:9)
    at processTimers (internal/timers.js:500:7)
    at _deployOne (/Users/namnguyen/Workspace/blockchain/smart-contract-programming/hardhat-fund-me/node_modules/hardhat-deploy/src/helpers.ts:1002:24)
    at Object.module.exports [as func] (/Users/namnguyen/Workspace/blockchain/smart-contract-programming/hardhat-fund-me/deploy/01-deploy-fund-me.js:13:34)
    at DeploymentsManager.executeDeployScripts (/Users/namnguyen/Workspace/blockchain/smart-contract-programming/hardhat-fund-me/node_modules/hardhat-deploy/src/DeploymentsManager.ts:1219:22)
    at DeploymentsManager.runDeploy (/Users/namnguyen/Workspace/blockchain/smart-contract-programming/hardhat-fund-me/node_modules/hardhat-deploy/src/DeploymentsManager.ts:1052:5)
  Error: ERROR processing /Users/namnguyen/Workspace/blockchain/smart-contract-programming/hardhat-fund-me/deploy/01-deploy-fund-me.js:
  TypeError: Cannot read property 'length' of undefined
      at getFrom (node_modules/hardhat-deploy/src/helpers.ts:1713:14)
      at fetchIfDifferent (node_modules/hardhat-deploy/src/helpers.ts:939:38)
      at processTicksAndRejections (internal/process/task_queues.js:95:5)
      at runNextTicks (internal/process/task_queues.js:64:3)
      at listOnTimeout (internal/timers.js:526:9)
      at processTimers (internal/timers.js:500:7)
      at _deployOne (node_modules/hardhat-deploy/src/helpers.ts:1002:24)
      at Object.module.exports [as func] (deploy/01-deploy-fund-me.js:13:34)
      at DeploymentsManager.executeDeployScripts (node_modules/hardhat-deploy/src/DeploymentsManager.ts:1219:22)
      at DeploymentsManager.runDeploy (node_modules/hardhat-deploy/src/DeploymentsManager.ts:1052:5)
      at DeploymentsManager.executeDeployScripts (node_modules/hardhat-deploy/src/DeploymentsManager.ts:1222:19)
      at processTicksAndRejections (internal/process/task_queues.js:95:5)
      at runNextTicks (internal/process/task_queues.js:64:3)
      at listOnTimeout (internal/timers.js:526:9)
      at processTimers (internal/timers.js:500:7)
      at DeploymentsManager.runDeploy (node_modules/hardhat-deploy/src/DeploymentsManager.ts:1052:5)
      at Object.fixture (node_modules/hardhat-deploy/src/DeploymentsManager.ts:315:9)
      at Context.<anonymous> (test/unit/FundMe.test.js:12:9)

Thanks for your help!

Answer 1

Usually, this is because the config of namedAccount is missing in the file hardhat.config.js. The config tells the plugin hardhat-deploy which account it should use to deploy contracts.

Check the hardhat.config.js, and add the snippet codes below to the file:

  namedAccounts: {
    deployer: {
      default: 0, 
      1: 0, 
    },