Lesson 9: Assertion Error: + expected - actual

[Jatinkkalra]

Overview

I am trying to run the test for fulfillRandomWords function using yarn hardhat test --grep "fulfillRandomWords" command.

I am facing this error:

Lottery Unit Test
    fulfillRandomWords
Local network detected (Mock)! Deploying Mocks....
---------------------------------
Deploying Lottery: Local network detected (Mock)! Deploying Mocks....
vrfCoordinatorV2Address is 0x5FbDB2315678afecb367f032d93F642f64180aa3
      ✔ can only be called after performUpkeep (52ms)
Found the event!
0x70997970C51812dc3A010C7d01b50e0d17dc79C8
0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266
0x70997970C51812dc3A010C7d01b50e0d17dc79C8
0x3C44CdDdB6a900fa2b585dd299e03d12FA4293BC
0x90F79bf6EB2c4f870365E785982E1f101E93b906
      1) picks a winner and emits to a winner list, changes Lottery status to OPEN, resets the lottery array & timestamp, and send money or reverts error otherwise


  1 passing (5s)
  1 failing

  1) Lottery Unit Test
       fulfillRandomWords
         picks a winner and emits to a winner list, changes Lottery status to OPEN, resets the lottery array & timestamp, and send money or reverts error otherwise:

      AssertionError: expected '10000009929483662726540' to equal '10000029929483662726540'
      + expected - actual

      -10000009929483662726540
      +10000029929483662726540

      at FragmentRunningEvent.<anonymous> (test\unit\Lottery.test.js:219:26)
      at processTicksAndRejections (node:internal/process/task_queues:95:5)
      at runNextTicks (node:internal/process/task_queues:64:3)
      at listOnTimeout (node:internal/timers:538:9)
      at processTimers (node:internal/timers:512:7)



error Command failed with exit code 1.

I have tried adding gasCost but I am facing the same error still. The gasCost code has been commented out from the function for the time-being.

My Repo: https://github.com/Jatinkkalra/hardhat-smartcontract-lottery

If anyone can help, it would be mean a lot. Thanks a ton in advance! 🙏

[HarshDev56]

@Jatinkkalra in your Lottery.test.js file you need to call .toString() inside .add() not outside
replace this line

assert.equal(
                    winnerEndingBalance.toString(),
                    winnerStartingBalance
                      .add(
                        lotteryEntranceFee
                          .mul(additionalEntrants)
                          .add(lotteryEntranceFee)
                        // .add(gasCost) // Include gas cost in the calculation
                      )
                      .toString()
                  );

with

assert.equal(
                    winnerEndingBalance.toString(),
                    winnerStartingBalance
                      .add(
                        lotteryEntranceFee
                          .mul(additionalEntrants)
                          .add(lotteryEntranceFee)
                            .toString()
                        // .add(gasCost) // Include gas cost in the calculation
                      )
                    
                  );

[Jatinkkalra]

@HarshDev56 I tried that first but it was giving me a "BigNumber" error. Here is the error prompt:

yarn hardhat test --grep "fulfillRandomWords"
yarn run v1.22.19
warning package.json: No license field

  Lottery Unit Test
    fulfillRandomWords
Local network detected (Mock)! Deploying Mocks....
---------------------------------
Deploying Lottery: Local network detected (Mock)! Deploying Mocks....
vrfCoordinatorV2Address is 0x5FbDB2315678afecb367f032d93F642f64180aa3
      ✔ can only be called after performUpkeep (85ms)
Found the event!
0x70997970C51812dc3A010C7d01b50e0d17dc79C8
0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266
0x70997970C51812dc3A010C7d01b50e0d17dc79C8
0x3C44CdDdB6a900fa2b585dd299e03d12FA4293BC
0x90F79bf6EB2c4f870365E785982E1f101E93b906
AssertionError: expected '10000009929483662726540' to equal BigNumber{ …(2) }
    at FragmentRunningEvent.<anonymous> (C:\Users\hardhat-smartcontract-lottery\hardhat-smartcontract-lottery\test\unit\Lottery.test.js:219:26)
    at processTicksAndRejections (node:internal/process/task_queues:95:5) {
  showDiff: true,
  actual: '10000009929483662726540',
  expected: BigNumber { _hex: '0x021e1a4b1e6fa447158c', _isBigNumber: true },
  operator: 'deepStrictEqual'
}
      1) picks a winner and emits to a winner list, changes Lottery status to OPEN, resets the lottery array & timestamp, and send money or reverts error otherwise


  1 passing (5s)
  1 failing

  1) Lottery Unit Test
       fulfillRandomWords
         picks a winner and emits to a winner list, changes Lottery status to OPEN, resets the lottery array & timestamp, and send money or reverts error otherwise:
     AssertionError: expected '10000009929483662726540' to equal BigNumber{ …(2) }
      at FragmentRunningEvent.<anonymous> (test\unit\Lottery.test.js:219:26)
      at processTicksAndRejections (node:internal/process/task_queues:95:5)



error Command failed with exit code 1.

[Jatinkkalra]

@HarshDev56 I have updated the github file too, with the solution you recommended.
Either I am facing a minor "expected vs actual" error, or a "BigNumber" error.

My repo: https://github.com/Jatinkkalra/hardhat-smartcontract-lottery

[alfaqi]

1- issue with BigNumber must toString() be out of add function, like this

assert.equal(
    winnerEndingBalance.toString(),
    winnerStartingBalance
      .add(
        lotteryEntranceFee
          .mul(additionalEntrants)
          .add(lotteryEntranceFee)
      )
      .toString()
  );

the issue of calculating the balance of winner was with closing } of for loop, , like this

for (
    let i = startingAccountIndex;
    i < startingAccountIndex + additionalEntrants;
    i++
  ) {
    const accountConnectedToLottery = lottery.connect(accounts[i]); // connecting to each account one by one
    await accountConnectedToLottery.enterLottery({
      value: lotteryEntranceFee,
    });
  }

then the rest of code
I hope it helps

[Jatinkkalra]

This helped! Thanks a lot ser @alfaqi ! 🙏🙌