README

A course at Chapman University Spring 2023 as a section of CPSC 298, the Computer Science Colloquium, which offers one credit courses (one lecture per week) on a current topic of interest. The title of this section is

Introduction to Smart Contracts

(created by Alexander Kurz and Ronan Kearns from Chapman and Jeff Turner and Stephen Preston from ComposeDAO)

Lectures: Feb 1 - May 10 in Keck 153, Wed 12-1pm. No classes March 22 (Spring break).
Discord: We use Discord for discussions and further teaching materials.

The purpose of the course is to give a hands-on introduction in how to develop a dApp using smart contracts.

• Lecture by lecture

Required Steps for Testing and Deployment

Install Foundry -> https://book.getfoundry.sh/getting-started/installation.html

npm i 
forge install 

Configure .env file -> see .env.example. (Go to your Metamask, follow "Goerli test network->Account details->Export private key" and enter the private key in your .env (for the PRIVATE_KEY variables); make an account with alchemy, create a test app for the Ethereum chain on the Goerli network and fill in the value for ALCHEMY_API_KEY.)

This framework has been written to use various testnets and mainnets. Test ETH has been encoded into the tasks for localhost deployment. For testnets, test ETH, BNB, or ETC is required which can be received from their corresponding faucets. An .env is used for running on other networks outside of localhost.

Configured Networks:

• Localhost
• Goerli. Faucet: https://goerlifaucet.com/
• Sepolia. Faucet: https://sepoliafaucet.com/
• BSC Testnet. Faucet: https://testnet.bnbchain.org/faucet-smart
• BSC.
• Mordor. Faucet: https://easy.hebeswap.com/#/faucet

NPM Commands

npm run compile # runs hardhat compile
npm run clean # runs hardhat clean
npm run test # runs unit tests via Forge

On some systems npm run compile raises an error ¹ that can be circumvented by running nvm install 14.

Hardhat Tasks

Deployment

To deploy your contract use

npx hardhat --network <network_name> deploy --contract <contract_name> --arg <constructor_argument>

For example,

npx hardhat --network sepolia deploy --contract Treasury --arg 0x7169D38820dfd117C3FA1f22a697dBA58d90BA06

Exercise: Inspect Treasury.sol and explain what role the argument 0x7169D38820dfd117C3FA1f22a697dBA58d90BA06 plays. Google it and look it up on Etherscan. It is a well-known stable coin.

If you get Error: insufficient funds go to a faucet (see links above), use your Alchemy login, and enter the wallet address you get from your Metamask wallet. If everything worked you see in your terminal

Contract deployed to: <deployed_contract_address>

Example: When we run the command above, our smart contract was created on the Sepolia testnet at 0x1b1cDCdBEFd2088C32ca0655CE01E5124F39C116.

Verification

To "verify" your contract (ie to display the code on Etherscan) run

npx hardhat --network <network_name> verify <deployed_contract_address> <constructor_argument>

If you get Error [...] no API token was found go to Etherscan, create an account, get an API-key and add it to your .env

Now you should be able to interact via your Metamask wallet with your contract on the testnetwork.

Summary of hardhat commands:

npx hardhat # lists all available hardhat tasks

npx hardhat --network <network_name> balance --account <account_address> # retrieves account balance on specified network

npx hardhat --network <network_name> deployproxy --contract <contract_name> # Deploys provided upgradeable contract to specified network. Proxy type is UUPS

npx hardhat --network <network_name> flatten <contract_file_path> > <output_file_path> # Flattens contracts and dependecies to output file

npx hardhat --network <network_name> initialize --contract <contract_name> --contract-address <deployed_contract_address> # Initializes provided upgradeable contract on specified network

npx hardhat --network <network_name> validateupgrade --contract <new_contract_name> --proxy-address <deployed_proxy_contract_address> # Validates new implementation contract without deploying it

npx hardhat --network <network_name> deploy --contract <contract_name> --arg <constructor_argument> # Deploys given contract to specified network

npx hardhat --network <network_name> verify <deployed_contract_address> <constructor_argument> # verifies source code on Etherscan or BSCSCAN. Supported networks are Goerli, BSC, BSC Testnet

Troubleshooting

If you get an error similar to this:

[Error: ENOENT: no such file or directory, open 'C:\Users\<USER>\src\introduction-to-smart-contracts\artifacts\build-info\02c99f9d2dcfd295a0c0fe2cc9481c42.json'] {
  errno: -4058,
  code: 'ENOENT',
  syscall: 'open',
  path: 'C:\\Users\\<USER>\\src\\introduction-to-smart-contracts\\artifacts\\build-info\\02c99f9d2dcfd295a0c0fe2cc9481c42.json'
}

Then run: npm run clean

Deno and Aleph

Setting up a Deno webserver linked to Github

https://spreston8-cspc-298-website.deno.dev/: An example webserver that can be used to donate money to a project. It runs on Deno and Aleph.js and includes wallet connect.

Steps to deploy your own site to https://deno.com/deploy

1. Go to https://deno.com/deploy and sign up/sign in. Needs github access.
2. Make sure your repo is uptodate with this one. In particular, it should contain the frontend folder.
3. Create a new project and link your github repo to project with entrypoint being frontend/server.ts. Choose "automatic".
4. Modify frontend/sponsorship.ts to include your contract address for goerli testnet. Contract must include deposit function found in Treasury.sol
5. Push your changes to update published site

The result of following these steps in the current repo is here.

Installing Deno locally

If you want to install Deno locally:

Deno installation

Aleph.js

Run the webserver locally:

cd frontend
deno task dev

---

Footnotes

1. Error message occaionally seen after npm run compile:

   node_modules/hardhat/internal/cli/cli.js:129
       let taskName = parsedTaskName ?? task_names_1.TASK_HELP;
   
   SyntaxError: Unexpected token '?'
   at Object.compileFunction (vm.js:344:18)
   at wrapSafe (internal/modules/cjs/loader.js:1048:15)
   at Module._compile (internal/modules/cjs/loader.js:1082:27)
   at Object.Module._extensions..js (internal/modules/cjs/loader.js:1138:10)
   at Module.load (internal/modules/cjs/loader.js:982:32)
   at Function.Module._load (internal/modules/cjs/loader.js:875:14)
   at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
   at internal/main/run_main_module.js:17:47
   

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