Lesson 7: Error in the second test for "withdraw" function

[Varshacs004]

I can't figure out why my startingDeployerBalance.add(startingFundMeBalance).toString() and endingDeployerBalance.add(gasCost).toString() are not equal.
This is the code for testing the 2nd test of withdraw function in FundMe.test.js :

it("allows us to withdraw with multiple funders", async function () {
            //Arrange
            const accounts = await ethers.getSigners()
            for (let i = 0; i < 6; i++) {
                const fundMeConnectedContract = await fundMe.connect(
                    accounts[i]
                )
                fundMeConnectedContract.fund({ value: sendValue })
            }
            const startingFundMeBalance = await fundMe.provider.getBalance(
                fundMe.address
            )
            console.log(
                "startingFundMeBalance: " +
                    startingFundMeBalance / 1000000000000000000
            )
            const startingDeployerBalance = await fundMe.provider.getBalance(
                deployer
            )

            console.log(
                "startingDeployerBalance: " +
                    startingDeployerBalance / 1000000000000000000
            )

            //Act
            const transactionResponse = await fundMe.withdraw()
            const transactionReceipt = await transactionResponse.wait(1)
            const { gasUsed, effectiveGasPrice } = transactionReceipt
            const gasCost = gasUsed.mul(effectiveGasPrice)
            const endingFundMeBalance = await fundMe.provider.getBalance(
                fundMe.address
            )
            const endingDeployerBalance = await fundMe.provider.getBalance(
                deployer
            )
            console.log(
                "Final Deployer Balance: " +
                    startingDeployerBalance
                        .add(startingFundMeBalance)
                        .toString() /
                        1000000000000000000
            )
            console.log(
                "endingDeployerBalance: " +
                    endingDeployerBalance.add(gasCost).toString() /
                        1000000000000000000
            )

            //Assert
            assert.equal(endingFundMeBalance, 0)
            assert.equal(
                startingDeployerBalance.add(startingFundMeBalance).toString(),
                endingDeployerBalance.add(gasCost).toString()
            ) /**@notice add function makes it easier for adding big numbers */

            //Check if funders array is reset properly
            await expect(fundMe.funders(0)).to.be.reverted

            for (let i = 1; i < 6; i++) {
                assert.equal(
                    await fundMe.addressToAmountFunded(accounts[i].address),
                    0
                )
            }
        })

and this is the output:

FundMe
    withdraw
startingFundMeBalance: 1
startingDeployerBalance: 9997.996858935652
Final Deployer Balance: 9998.99685893565
endingDeployerBalance: 10004.996858935652
      1) allows us to withdraw with multiple funders


  0 passing (620ms)
  1 failing

  1) FundMe
       withdraw
         allows us to withdraw with multiple funders:

      AssertionError: expected '9998996858935651281644' to equal '10004996858935651281644'
      + expected - actual

      -9998996858935651281644
      +10004996858935651281644
      
      at Context.<anonymous> (test/unit/FundMe.test.js:138:20)
      at processTicksAndRejections (node:internal/process/task_queues:96:5)
      at runNextTicks (node:internal/process/task_queues:65:3)
      at listOnTimeout (node:internal/timers:528:9)
      at processTimers (node:internal/timers:502:7)



error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

when I run this command:

yarn hardhat test --grep "withdraw with multiple funders"

[Varshacs004]

I forgot to add the await keyword to the fundMeConnectedContract.fund({ value: sendValue }) line at the starting of the test "allows us to withdraw with multiple funders". I also changed the for loop constraints from for (let i = 0; i < 6; i++) to for (let i = 1; i < 6; i++).

This is before correction:

for (let i = 0; i < 6; i++) {
                const fundMeConnectedContract = await fundMe.connect(
                    accounts[i]
                )
                fundMeConnectedContract.fund({ value: sendValue })
            }

and this is after correction:

for (let i = 1; i < 6; i++) {
                const fundMeConnectedContract = await fundMe.connect(
                    accounts[i]
                )
                await fundMeConnectedContract.fund({ value: sendValue })
            }

Could someone explain in detail why the code didn't work when the await keyword was not added?

[Muhammad-Abdullah012]

Without await keyword, code was not waiting for the transaction to complete, the next iteration was running,.. and so on. It's possible that before last few transactions completed, the code reached at point where it was testing the assertion.

[Varshacs004]

Thank you for the explanation...