lesoon- 7 mocks- deploy

[TimeKeyRoll]

Hi! I am unable to understand what's benifit of mentioning 8 decimals but wei has 18 zeros. why it is thera nd whats the purpose of this?
could anyone please explain..?
and also it is using INITIAL_ANSWER: 2000 . Whee is this 2000 number coming from?

Thankyou very much in advance.

[othaime-en]

Hello @MasterofBlockchain.
Quick refresher, as you know, Mocks allow us to deploy a minimal version of a contract if it does not exist on a chain e.g. the hardhat network. And since our hardhat network doesn't have the AggregatorV3interface contract that we need to calculate the price of ETH in USD, we deploy a minimal version of it locally in our hardhat network through our MockV3Aggregator file.

If you can remember, in our MockV3Aggregator.sol file ( ./contracts/mocks/MockV3Aggregator.sol), we imported this mock from our local @chainlink/contracts module. However if look at this Mock that we imported (You can go through it in the github repo by chainlink), the constructor function needs two variables: _decimals and _initialAnswer.
This simply means that for us to run our mock contract, we need these two variables. Therefore we created them in our helper-hardhat file as DECIMALS and INITIAL_ANSWER.

Now to answer your question, the INITIAL_ANSWER simply represents the starting value of the priceFeed i.e. the value of 1 ETH in USD. You can basically put any value you want not necessarily 2000. Since we are working locally, the only thing we are concerned about is if the priceFeed is working, not if it gives us the correct value of 1 ETH in USD.
The DECIMALS value does not represent the decimals found in wei. It is a predefined value for the AggregatorV3Interface contract which describes the number of decimals we need to add to our INITIAL_ANSWER for it to be represented correctly and it is 8. You can look it up here on etherscan where the actual contract is hosted. If you read no 3 (decimals) you'll find the value of 8 there.

Don't worry too much about what is happening here and what it means at the moment. Give it time, you'll gradually understand as you advance. The only thing you need to know in this section is that we are using a predefined value of 8 for the DECIMALS value and our INITIAL_ANSWER is the starting price in USD that we chose to give to 1 ETH. We then append the 8 DECIMALS value to our INITIAL_ANSWER value. so 2000 becomes 2000_00000000

[TimeKeyRoll]

Thank you very much brother. It has cleared the doubts. Appreciated.

[othaime-en]

Welcome. Happy coding!