Lesson 7 - 11:36 - Why are we adding gasCost to the endingDeployerBalance?

[alwayscommit]

assert.equal(
                //BigNumber.add() function is better to perform math operations, makes it easier
                startingFundMeBalance.add(startingDeployerBalance),
                endingDeployerBalance.add(gasCost).toString()
            )

In this test case, could someone please explain why the is "deployer" getting the gasCost?
Here, is the "deployer" considered as the only node? In a real-world fund-me project, will the deployers of the contract get the gasCost? Or will the people running Ethereum nodes will get the gasCost?

[PatrickAlphaC]

Whoever calls the transaction, pays the gas costs associated with it. In this function, we are calling the withdraw function.

Take this scenario.

deployer address has 1 ETH
FundMe contract has 1 ETH

If the deployer address calls the withdraw function and pulls the 1 ETH out of the FundMe contract, how much ETH will they have?

1 + 1 = 2 ETH... but they also paid the gas of calling the withdraw function.

So they would have 1 + 1 - (gascosts) = ~1.9(ish)

In our tests, we want to account for the gas costs to make it accurate.

So, following our example, if you take the test:

assert.equal(
                //BigNumber.add() function is better to perform math operations, makes it easier
                startingFundMeBalance.add(startingDeployerBalance),
                endingDeployerBalance.add(gasCost).toString()
            )

We are saying that:

Before we call `withdraw` we have 1 + 1 ETH (1 in FundMe and 1 in Deployer)
After we call `withdraw` we have 2 - gascost of withdraw in the deployer account

Does this make sense?

[alwayscommit]

Oh, thank you for the explanation. I got it.

Just to ensure that the test passes, we have to add the gasCost to the deployer because they paid this gasCost during the transaction and the balance would fall below 2 ETH, so just to ensure that the test case is correct, we "add" this gasCost back to the deployer's current balance check. It's only for the test case, and in reality their balance would be below 2 ETH.

I was confused about why are we doing a check by adding gasCost, we should do an absolute check on the deployer's balance that is below 2 ETH, but it has the same effect in the end I guess.

Thanks a lot!