Lesson 9 - performUpKeep unit test - approach to know the winner

[GJanuario]

Hello there, guys!

I got a little confused about how Patrick finds out the raffle winner on this unit test.

In this timestamp, Patrick says "we gotta make sure our winner is correct", because we want to do some assertion on his balance.

With some console.log, in this timestamp, he finds out winner is player on index number 1.

Console.logs to find out the winner (only present during the video):

Final code during the video (winnerStartingBalance defined as accounts[1] balance):

This is the code on the repository for Lesson 9 (deleted the comments so it would have my comments only). Apparently the code was changed to accounts[2]:

...
await new Promise(async (resolve, reject) => {
    raffle.once("WinnerPicked", async () => {
        console.log("WinnerPicked event fired!")
        try {
            const recentWinner = await raffle.getRecentWinner()
            const raffleState = await raffle.getRaffleState()
            const winnerBalance = await accounts[2].getBalance() // also accounts[2] information
            const endingTimeStamp = await raffle.getLastTimeStamp()
            await expect(raffle.getPlayer(0)).to.be.reverted
            assert.equal(recentWinner.toString(), accounts[2].address) // also accounts[2] information
            assert.equal(raffleState, 0)
            assert.equal(
                winnerBalance.toString(), 
                startingBalance
                    .add(
                        raffleEntranceFee
                            .mul(additionalEntrances)
                            .add(raffleEntranceFee)
                    )
                    .toString()
            )
            assert(endingTimeStamp > startingTimeStamp)
            resolve()
        } catch (e) { 
            reject(e)
        }
    })

    const tx = await raffle.performUpkeep("0x")
    const txReceipt = await tx.wait(1)
    // why is the balance for accounts[2] being selected here? Is it guaranteed this is going to be the winner?
    const startingBalance = await accounts[2].getBalance()
    await vrfCoordinatorV2Mock.fulfillRandomWords(
        txReceipt.events[1].args.requestId,
        raffle.address
    )
})
...

My question is: I understand that player number 1 was the winner on that raffle, but how is it that we know player number 1 is always going to win the raffle on that unit test?

I feel like I'm missing something, obviously.

[krakxn]

Can you outline the specific code snippet you are doubtful of? So I can elaborate.

[GJanuario]

Updated with content from the video and the repository

[krakxn]

Updated with content from the video and the repository

It is because, as Patrick explains here - our mocks always has the same winner. Hope this helps you!

[GJanuario]

Knew I was missing something!
Thanks a lot!