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About

This file will list issues/updates by timestamp. If you have an issue that you don't see here, please make an issue on this repo.

Faucet Issues

  • If you have any issues with a faucet, please try another testnet. You'll have to update some contract addresses based on the testnet you're working on. You can find the most up to date faucets here.
  • If the Rinkeby faucet isn't working, you can use a kovan faucet, just be sure to use Kovan Etherscan and Kovan in your Metamask!
  • Big Update: New Rinkeby Faucet Located Here
  • You can find Backup Faucets here

Linting issues

If you see something along the lines of:

ParserError: Source "OpenZeppelin/[email protected]/contracts/access/Ownable.sol" not found: File not found.
import "@openzeppelin/contracts/access/Ownable.sol";

In your vscode, these and be safely ignored. However you can also add to your settings to ignore these.

  1. Create a .vscode folder at the root of your project.
  2. Create a file called settings.json
  3. Add the following code:
{
  "solidity.remappings": [
    "@chainlink/=/Users/patrick/.brownie/packages/smartcontractkit/[email protected]",
    "@openzeppelin/=/Users/patrick/.brownie/packages/OpenZeppelin/[email protected]"
  ]
}

Or whatever version your @chainlink and @openzeppelin contracts need. For example: Screen Shot 2021-10-05 at 6 01 45 PM

Note: remember this is an example, you must provide the actual location on which your .brownie folder is located. For more info on on this please refer here.

Integration Testing Issues

  • In some integration tests, we do something like time.sleep(60). Sometimes, you'll have to do much longer, we've had reports go up to time.sleep(300). So, if you want to try that, go get a coffee break while your integration test runs!

Python related issues

  • In some environments Web3.py may not work due to the Cytools error, which means your computer lacks some C language libraries in order to execute.

    Here you can find a detailed guide about how to solve the problem.

Lesson 3:

  • 2:37:05 Kovan vs Rinkeby
    • Our FundMe.sol needs to be deployed to the rinkeby chain to work, but if you go to try the price feeds from the Chainlink docs using the remix link, that one has the kovan price feeds in it, so needs to be deployed to kovan.
    • If you want to test the price feeds from the video using the Chainlink docs remix link, you'll need to follow the steps to get kovan ETH.

Lesson 4:

  • 3:43:52 Installing solcx version 0.6.0
    • In the video, we forgot to do 2 things in order to compile our solidity code:
      • Import install_solc, so we need to change this line:
        • from solcx import compile_standard
      • To this line:
        • from solcx import compile_standard, install_solc
      • And then, we need to add a line right before we run the compile_standard code:
        • install_solc("0.6.0")
  • 4:00:00 Issue with ganache and web3.py
    • As of 5.25.0 of web3.py, we now need to add gasPrice to our transactions with a local ganache chain.
    • Adding "gasPrice": w3.eth.gas_price, should fix your issue in the transactions.

Full Example:

transaction = SimpleStorage.constructor().buildTransaction(
    {
        "chainId": chain_id,
        "gasPrice": w3.eth.gas_price,
        "from": my_address,
        "nonce": nonce,
    }
)

  • 3:56:20 Colorized Brackets.

    • The referenced extension has been deprecated due to VS code adding native functionality. To enable the new setting search for bracket and check the checkbox below: Editor > Bracket Pair Colorization: Enabled

      image

  • 3:55:09 Confusing network ID and chain ID

    • In the video the network ID is copied instead of the chain id. Whenever the terms Network ID and Chain ID are used without distinction, it should be noted that both IDs can be different for a server such as Ganache. As you can see here, Ganache can be using different IDs.
>>> from web3 import Web3
>>> w3 = Web3(Web3.HTTPProvider("http://127.0.0.1:8545"))
>>> w3.eth.chain_id
1337
>>> w3.net.version
'5777'
>>>

Lesson 6

  • 5:44:00
    • In the video, the getEntranceFee() function returns (minimumUSD * precision) / price
    • Integer divisions are rounded towards 0 in Solidity, so this function will almost always return an amount worth slightly less than our minimum price. It makes it unusable with the fund() function because the transaction will revert everytime.
    • To fix it we can round up the result
    • getEntranceFee() function should return ((minimumUSD * precision) / price) + 1
    • This fix has been merged and you can read more explanation about the issue here

Lesson 7

In the video, we use Chainlink VRF v1 and the documentation has been updated to V2. You can view the V1 documentation here

  • Looking for the VRF Coordinator contract by yourself will probably bring you to the v2 address of it. Make sure to use the v1 VRF Coordinator contract in the brownie-config.yaml file, because it won't work with the v2 contract. The repository has already the correct contract address.

  • 8:06:54ish

    • In the video, we use events exclusivly to test our contracts, however, we could have also used tx.return_value to get the return value of a function.
    • However, it's still best practice to learn how to use events, especially when updating mappings!

  • 8:10:20ish

    • In the video, starting_balance_of_account and balance_of_lottery are retrieved AFTER lottery.endLottery()
    • For correctness those 2 statements should be run BEFORE lottery.endLottery()
    • The tests pass because starting_balance_of_account == account.balance() (L81) and lottery.balance() is already 0
    • This is a subtle bug in the test, which also showcases a problem with tests - we have no one to test the tests ;) Still, having tests is better than not having them, just don't put all your assurances into them

Lesson 10

  • The Aave testnet site has moved from https://testnet.aave.com to https://staging.aave.com and some of the functionality is lost :(
  • For our repay_all function, we originally had:
repay_all(AMOUNT, lending_pool, account)

But it should be:

repay_all(Web3.toWei(amount_dai_to_borrow, "ether"), lending_pool, account)

We want to pay back the DAI not the ETH! Just remember, you'll still have a vveerrrryyyy small amount of DAI borrowed because of interest. If you see something with an E in it, you did it right!