# Using Foundry [Foundry](https://github.com/foundry-rs/foundry/) is a smart contract development toolchain. Foundry manages your dependencies, compiles your project, runs tests, deploys, and lets you interact with the chain from the command line and via Solidity scripts. Forge is a command-line tool that ships with Foundry. Forge tests, builds, and deploys your smart contracts. Forge supports contract verification out of the box () ## Get Started ### **1)** Install Foundry ### **2) Create a project** To start a new project with Foundry, use [`forge init`](https://book.getfoundry.sh/reference/forge/forge-init.html): ``` forge init foundry_verify_demo ``` Let's check out what `forge` generated for us: ``` cd foundry_verify_demo tree . -d -L 1 . ├── lib ├── script ├── src └── test 4 directorie ``` ## Config File foundry.toml ``` [profile.default] src = 'src' out = 'out' libs = ['lib'] solc = "0.8.13" eth-rpc-url = "https://rpc-testnet.kcc.network" optimizer = true optimizer-runs = 10_000_000 # See more config options https://github.com/foundry-rs/foundry/tree/master/config ``` ### Deploying Forge can deploy smart contracts to a given network with the [`forge create`](https://book.getfoundry.sh/reference/forge/forge-create.html) command. Forge can deploy only one contract at a time. To deploy a contract, you must provide a RPC URL (env: `ETH_RPC_URL`) and the private key of the account that will deploy the contract. Deploy the `MyContract` to the network: ``` forge create --rpc-url --private-key src/MyContract.sol:MyContract compiling... success. Deployer: 0xa735b3c25f... Deployed to: 0x4054415432... Transaction hash: 0x6b4e0ff93a... ``` Solidity files may contain multiple contracts. `:MyContract` above specifies which contract to deploy from the `src/MyContract.sol` file. Use the `--constructor-args` flag to pass arguments to the constructor: #### KCC Testnet Example ```solidity // SPDX-License-Identifier: UNLICENSED pragma solidity ^0.8.13; contract TestVerify { string public name; uint256 public number; constructor( string memory _name, uint256 _number ) { name=_name; number = _number; } function setNumber(uint256 newNumber) public { number = newNumber; } function increment() public { number++; } } ``` Ddeploy the `TestVerify` to the KCC Testnet: ``` forge create \ --rpc-url https://rpc-testnet.kcc.network/ \ --constructor-args "counter-verify" 123 \ --private-key \ src/TestVerify.sol:TestVerify \ --constructor-args "" \ --legacy [⠢] Compiling... No files changed, compilation skipped Deployer: 0xC4E82486c745dF7Ff21498A32914558e255dfffa Deployed to: 0x1E8e3E6d1a71a6267F199A5568f88A00aa4d10C4 Transaction hash: 0x66ca760f1532aacf383da0c747bddf3f81d1b6dec10846c9b45d3bded50446da ``` Additionally, we can tell Forge to verify our contract on Etherscan, Sourcify or Blockscout, if the network is supported, by passing `--verify`. ``` forge create \ --rpc-url https://rpc-testnet.kcc.network/ \ --constructor-args "counter-verify" 123 \ --private-key \ src/TestVerify.sol:TestVerify \ --verify \ --verifier=blockscout \ --verifier-url=https://scan-testnet.kcc.network/api \ --legacy [⠢] Compiling... No files changed, compilation skipped Deployer: 0xC4E82486c745dF7Ff21498A32914558e255dfffa Deployed to: 0x713b499f4cD5E4f65CaD22B4245Cd38ece8285eD Transaction hash: 0x3f07b8e249241254c051d19cd09f10561f36984a2509c5d1b576629490bb34fd Starting contract verification... Waiting for blockscout to detect contract deployment... Start verifying contract `0x713b499f4cd5e4f65cad22b4245cd38ece8285ed` deployed on 322 Submitting verification for [src/TestVerify.sol:TestVerify] "0x713b499f4cD5E4f65CaD22B4245Cd38ece8285eD". Submitted contract for verification: Response: `OK` GUID: `713b499f4cd5e4f65cad22b4245cd38ece8285ed642b8f33` URL: https://scan-testnet.kcc.network/apiaddress/0x713b499f4cd5e4f65cad22b4245cd38ece8285ed Contract verification status: Response: `OK` Details: `Pending in queue` Contract verification status: Response: `OK` Details: `Pass - Verified` Contract successfully verified ``` ### Verifying a pre-existing contract If you are verifying an already deployed contract, read on. You can verify a contract on Etherscan, Sourcify or Blockscout with the [`forge verify-contract`](https://book.getfoundry.sh/reference/forge/forge-verify-contract.html) command. You must provide: * the contract address * the contract name or the path to the contract `:` Moreover, you may need to provide: * the constructor arguments in the ABI-encoded format, if there are any * [compiler version](https://etherscan.io/solcversions) used for build, with 8 hex digits from the commit version prefix (the commit will usually not be a nightly build). It is auto-detected if not specified. * the number of optimizations, if the Solidity optimizer was activated. It is auto-detected if not specified. * the chain ID Let's say you want to verify `TestVerify` (see above). You set the [number of optimizations](https://book.getfoundry.sh/reference/config/solidity-compiler.html#optimizer_runs) to 1 million, compiled it with v0.8.13, and deployed it, as shown above, to the KCC Testnet (chain ID: 322). Note that `--num-of-optimizations` will default to 0 if not set on verification, while it defaults to 200 if not set on deployment, so make sure you pass `--num-of-optimizations 200` if you left the default compilation settings. Here's how to verify it: ``` forge verify-contract \ --chain-id 322 \ --num-of-optimizations 1000000 \ --watch \ --constructor-args $(cast abi-encode "constructor(string,uint256)" "counter-verify" 123) \ --verifier=blockscout \ --verifier-url=https://scan-testnet.kcc.network/api \ --compiler-version v0.8.13+commit.abaa5c0e \ 0x1E8e3E6d1a71a6267F199A5568f88A00aa4d10C4 \ src/TestVerify.sol:TestVerify Submitting verification for [src/TestVerify.sol:TestVerify] "0x1E8e3E6d1a71a6267F199A5568f88A00aa4d10C4". Submitted contract for verification: Response: `OK` GUID: `1e8e3e6d1a71a6267f199a5568f88a00aa4d10c4642b9477` URL: https://scan-testnet.kcc.network/apiaddress/0x1e8e3e6d1a71a6267f199a5568f88a00aa4d10c4 Contract verification status: Response: `OK` Details: `Pending in queue` Contract verification status: Response: `OK` Details: `Pass - Verified` Contract successfully verified ``` It is recommended to use the [`--watch`](https://book.getfoundry.sh/reference/forge/forge-verify-contract.html#verify-contract-options) flag along with `verify-contract` command in order to poll for the verification result. If the `--watch` flag was not supplied, you can check the verification status with the [`forge verify-check`](https://book.getfoundry.sh/reference/forge/forge-verify-check.html) command: {% hint style="info" %} #### Tips: 1. Setting the `—verifier=blockscout` flag allows you to not specify any Api key. 2. While specifying `--verifier-url` flag omit the final slash (e.g., `--verifier-url=`[`https://scan-testnet.kcc.network/api`](https://scan-testnet.kcc.network/api)). Otherwise, you will encounter an “*Failed to deserialize response*” error. 3. You can specify most configuration options (e.g., evm version, disabling optimizations) via the usual Forge configuration (see ). 4. Use Cast's [`abi-encode`](https://book.getfoundry.sh/reference/cast/cast-abi-encode.html) to ABI-encode arguments. In this example, we ran `cast abi-encode "`constructor(string,uint256)`"` "counter-verify" 123 to ABI-encode the arguments. 5. KCC Mainnet Scan `--verifier-url=`[`https://scan.kcc.io/api`](https://scan.kcc.io/api) {% endhint %} ## Troubleshooting **EIP-1559 not activated** EIP-1559 is not supported or not activated on the RPC server. Pass the `--legacy` flag to use legacy transactions instead of the EIP-1559 ones. If you do development in a local environment, you can use Hardhat instead of Ganache. **Compiler version commit for verify** If you want to check the exact commit you are running locally, try: `~/.svm/0.x.y/solc-0.x.y --version` where `x` and `y` are major and minor version numbers respectively. The output of this will be something like: ```ignore solc, the solidity compiler commandline interface Version: 0.8.12+commit.f00d7308.Darwin.appleclang ``` Note: You cannot just paste the entire string "0.8.12+commit.f00d7308.Darwin.appleclang" as the argument for the compiler-version. But you can use the 8 hex digits of the commit to look up exactly what you should copy and paste from [compiler version](https://etherscan.io/solcversions).