Lesson 9: Why we have different balance during the tests?

[zjy-1998]

1. When I ran the unit test of Raffle.test.js, I found the balance was different during tests as below.

I can't figure out why this happened.

          describe("checkUpkeep", async function () {
              it("returns false if people haven't sent any ETH", async function () {
                  await network.provider.send("evm_increaseTime", [interval.toNumber() + 1])
                  await network.provider.send("evm_mine", [])
                  //   await raffle.checkUpkeep([])
                  const balance = await raffle.getBalance() // 0
                  const { upkeepNeeded } = await raffle.callStatic.checkUpkeep([]) // should return false because no balance
                  assert(!upkeepNeeded)
              })

              it("returns false if raffle isn't open", async function () {
                  await raffle.enterRaffle({ value: raffleEntranceFee })
                  await network.provider.send("evm_increaseTime", [interval.toNumber() + 1])
                  await network.provider.send("evm_mine", [])
                  await raffle.performUpkeep("0x") // send a blank bites object "0x";
                  const balance = await raffle.getBalance() // 10000000000000000
                  const raffleState = await raffle.getRaffleState() 
                  const { upkeepNeeded } = await raffle.callStatic.checkUpkeep([])
                  assert.equal(raffleState.toString() == "1", upkeepNeeded == false)
              })
          })

2. Additionally, what's the difference between using the [] and "0x" as the parameter to pass to checkUpkeep() and performUpkeep()?

About the code below,
3&4&5. why we call the performUpkeep()(which also calls the checkUpkeep()) before checkUpkeep(), rather than call the checkUpkeep() before performUpkeep()? And why we need to call twice checkUpkeep() during this test?
6. What's the difference between const varible and const {variable}, aka we define a variable with curly brackets or not?

              it("returns false if raffle isn't open", async function () {
                  await raffle.enterRaffle({ value: raffleEntranceFee })
                  await network.provider.send("evm_increaseTime", [interval.toNumber() + 1])
                  await network.provider.send("evm_mine", [])
                  await raffle.performUpkeep("0x") // send a blank bites object "0x";
                  const balance = await raffle.getBalance() // 10000000000000000
                  const raffleState = await raffle.getRaffleState() 
                  const { upkeepNeeded } = await raffle.callStatic.checkUpkeep([])
                  assert.equal(raffleState.toString() == "1", upkeepNeeded == false)
              })

[zjy-1998]

Something I may figure out:
why we call the performUpkeep()(which also calls the checkUpkeep()) before checkUpkeep(), rather than call the checkUpkeep() before performUpkeep()? And why we need to call twice checkUpkeep() during this test?
⬆️That's because this test is about testing the raffleState and upkeepNeeded . After performUpkeep(), raffleState should be CALCULATING from OPEN, upkeepNeeded should be true. Then after checkUpkeep(), Because the raffleState is CALCULATING now, so upkeepNeeded should be false.

[alymurtazamemon]

@zjy-1998

1. Your balance is updated in the second test because we deposit the fund using enterRaffle function.
2. [] & 0x both are ways to pass an empty array.
3. We are calling the performUpkeep, it will call the checkUpkeep internally and do all the calculations.
4. In this test we are checking returns false if raffle isn't open whether the raffle is open or not. so after calling performUpkeep we are getting the raffle state and checking here assert.equal(raffleState.toString() == "1", upkeepNeeded == false)
5. We are calling the checkUpkeep a second time to check whether upkeepNeeded is true or false. Because if raffle is in OPEN state it should return false and we are also checking in the same assert. assert.equal(raffleState.toString() == "1", upkeepNeeded == false)
6. const {variableName} this is called destructing in JavaScript, it means a function is returning an object and we need a variable with the give name const {variableName}. As you see in the contract that checkUpkeep is returning upkeepNeeded that same we are destructuring here.

[zjy-1998]

@alymurtazamemon
Got it! Thank you so much to answer all of my questions in such clear way!