cronos-contract-boilerplate contract example repo

.gitmodules

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+[submodule "cronos-contract-boilerplate/foundry/lib/forge-std"]
+	path = cronos-contract-boilerplate/foundry/lib/forge-std
+	url = https://github.com/foundry-rs/forge-std
+[submodule "cronos-contract-boilerplate/foundry/lib/openzeppelin-contracts"]
+	path = cronos-contract-boilerplate/foundry/lib/openzeppelin-contracts
+	url = https://github.com/OpenZeppelin/openzeppelin-contracts

cronos-contract-boilerplate/.gitignore

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+# Environment
+.env
+
+# IDE / OS
+.idea
+.vscode
+.DS_Store
+
+# Dependencies
+node_modules

cronos-contract-boilerplate/README.md

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+# Cronos contract boilerplate
+
+Example ERC20, ERC721 and ERC1155 contracts for the Cronos EVM chain, provided for three toolchains. Every subproject ships the same three contracts and can deploy and verify them on Cronos mainnet (chain id 25) and testnet (chain id 338).
+
+All contracts use OpenZeppelin `^5.6.0`, Solidity `0.8.28` and `evmVersion: cancun`. The contract sources are identical across all three.
+
+## Subprojects
+
+| Folder | Toolchain | Deploy | Verify |
+| --- | --- | --- | --- |
+| [`foundry`](foundry/README.md) | Foundry (forge) | `forge script` | `forge verify-contract` |
+| [`hardhat/v3`](hardhat/v3/README.md) | Hardhat 3 (viem + Ignition) | Ignition modules | `hardhat verify` |
+| [`hardhat/v2`](hardhat/v2/README.md) | Hardhat 2 (ethers + TypeScript) | `hardhat run` scripts | `hardhat verify` |
+
+Each folder is independent and has its own README, dependencies and setup steps.
+
+## Tests
+
+Every subproject ships the same test suite for all three contracts, covering
+metadata, the initial supply, minting under `MINTER_ROLE`, rejection of minting
+without that role, and the pause guard.
+
+| Folder | Command | Local chain |
+| --- | --- | --- |
+| `foundry` | `forge test` | in-process (forge) |
+| `hardhat/v3` | `npx hardhat test` | in-process (Hardhat) |
+| `hardhat/v2` | `npx hardhat test` | in-process (Hardhat) |
+
+None of them need RPC access, a funded wallet or a `.env` file.
+
+## Contracts
+
+- `MyERC20.sol` - ERC20 with Burnable, Pausable, Permit, AccessControl and Ownable.
+- `MyERC721.sol` - ERC721 with URIStorage, Burnable, Pausable, AccessControl and Ownable.
+- `MyERC1155.sol` - ERC1155 with Burnable, Pausable, Supply, AccessControl and Ownable.
+
+## Cronos networks
+
+| Network | Chain ID | RPC | Explorer |
+| --- | --- | --- | --- |
+| Mainnet | 25 | https://evm.cronos.com/ | https://explorer.cronos.com |
+| Testnet | 338 | https://evm-t3.cronos.com/ | https://explorer.cronos.com/testnet |
+
+## Verification
+
+Both Hardhat and Foundry verify programmatically against the Cronos Explorer API. The API key is passed either inside the explorer apiUrl (Hardhat) or with `--etherscan-api-key` (Foundry). See the [Cronos Explorer API documentation](https://explorer-api-doc.cronos.org/testnet/) for how to get a key.

cronos-contract-boilerplate/foundry/.env.example

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+# Private key of the deployment wallet (hex, with or without 0x prefix)
+PRIVATE_KEY=
+# Block explorer API keys - used to verify contracts on the Cronos Explorer
+CRONOS_EXPLORER_MAINNET_API_KEY=
+CRONOS_EXPLORER_TESTNET_API_KEY=

cronos-contract-boilerplate/foundry/.gitignore

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+# Foundry output
+out
+cache
+broadcast
+
+# Dependencies
+lib
+
+.env
+
+# IDE
+.idea
+.DS_Store
+.vscode

cronos-contract-boilerplate/foundry/README.md

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+# Cronos contract boilerplate: Foundry
+
+Example ERC20, ERC721 and ERC1155 contracts for Cronos EVM, built with Foundry (forge).
+
+Contracts use OpenZeppelin `^5.6.0`, Solidity `0.8.28` and `evmVersion: cancun`.
+
+## Contracts
+
+- `src/MyERC20.sol` - ERC20 with Burnable, Pausable, Permit, AccessControl and Ownable.
+- `src/MyERC721.sol` - ERC721 with URIStorage, Burnable, Pausable, AccessControl and Ownable.
+- `src/MyERC1155.sol` - ERC1155 with Burnable, Pausable, Supply, AccessControl and Ownable.
+
+## Setup
+
+Install Foundry if you have not already (see the [Foundry book](https://book.getfoundry.sh/getting-started/installation)):
+
+```bash
+curl -L https://foundry.paradigm.xyz | bash
+foundryup
+```
+
+Install the dependencies:
+
+```bash
+forge install foundry-rs/forge-std@v1.16.2
+forge install OpenZeppelin/openzeppelin-contracts@v5.6.0
+```
+
+The `@openzeppelin/` remapping is already set in `foundry.toml`.
+
+Copy the environment file and fill it in:
+
+```bash
+cp .env.example .env
+source .env
+```
+
+- `PRIVATE_KEY` - private key of the deployment wallet (needs CRO for gas).
+- `CRONOS_EXPLORER_MAINNET_API_KEY` / `CRONOS_EXPLORER_TESTNET_API_KEY` - explorer API keys for verification.
+
+See the [Cronos Explorer API documentation](https://docs.cronos.com/block-explorers/block-explorer-and-api-keys) for how to get an API key.
+
+## Build and test
+
+```bash
+forge build
+forge test
+```
+
+## Deploy
+
+```bash
+forge script script/MyERC20.s.sol:MyERC20Script --rpc-url cronos_testnet --broadcast
+forge script script/MyERC721.s.sol:MyERC721Script --rpc-url cronos_testnet --broadcast
+forge script script/MyERC1155.s.sol:MyERC1155Script --rpc-url cronos_testnet --broadcast
+```
+
+Swap `cronos_testnet` for `cronos_mainnet` to deploy to mainnet.
+
+## Verify
+
+```bash
+forge verify-contract <ADDRESS> src/MyERC20.sol:MyERC20 \
+  --chain-id 338 \
+  --verifier-url https://explorer-api.cronos.org/testnet/api/v2 \
+  --etherscan-api-key $CRONOS_EXPLORER_TESTNET_API_KEY \
+  --constructor-args $(cast abi-encode "constructor(string,string)" "My token name" "My token symbol")
+```
+
+`MyERC721` takes no constructor arguments (drop `--constructor-args`), and `MyERC1155` takes the metadata URI:
+
+```bash
+--constructor-args $(cast abi-encode "constructor(string)" "https://example.com/api/token/{id}.json")
+```
+
+For mainnet use `--chain-id 25`, `--verifier-url https://explorer-api.cronos.org/mainnet/api/v2` and `$CRONOS_EXPLORER_MAINNET_API_KEY`.

cronos-contract-boilerplate/foundry/foundry.lock

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+{
+  "lib/forge-std": {
+    "tag": {
+      "name": "v1.16.2",
+      "rev": "bf647bd6046f2f7da30d0c2bf435e5c76a780c1b"
+    }
+  },
+  "lib/openzeppelin-contracts": {
+    "tag": {
+      "name": "v5.6.0",
+      "rev": "56a3de2cea907c9a500d32e70c275f68393b7ba6"
+    }
+  }
+}

cronos-contract-boilerplate/foundry/foundry.toml

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+[profile.default]
+src = "src"
+out = "out"
+libs = ["lib"]
+solc = "0.8.28"
+evm_version = "cancun"
+optimizer = true
+optimizer_runs = 200
+remappings = ["@openzeppelin/=lib/openzeppelin-contracts/"]
+
+# Cronos EVM RPC endpoints
+[rpc_endpoints]
+cronos_mainnet = "https://evm.cronos.com/"
+cronos_testnet = "https://evm-t3.cronos.com/"
+
+# Cronos Explorer verification endpoints.
+# The API key is passed on the command line with --etherscan-api-key.
+[etherscan]
+cronos_mainnet = { key = "${CRONOS_EXPLORER_MAINNET_API_KEY}", chain = 25, url = "https://explorer-api.cronos.org/mainnet/api/v2" }
+cronos_testnet = { key = "${CRONOS_EXPLORER_TESTNET_API_KEY}", chain = 338, url = "https://explorer-api.cronos.org/testnet/api/v2" }

cronos-contract-boilerplate/foundry/script/MyERC1155.s.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.28;
+
+import {Script, console} from "forge-std/Script.sol";
+import {MyERC1155} from "../src/MyERC1155.sol";
+
+// Deploy with:
+// forge script script/MyERC1155.s.sol:MyERC1155Script --rpc-url cronos_testnet --broadcast
+contract MyERC1155Script is Script {
+    string constant TOKEN_URI = "https://example.com/api/token/{id}.json";
+
+    function run() external returns (MyERC1155 token) {
+        uint256 deployerKey = vm.envUint("PRIVATE_KEY");
+
+        vm.startBroadcast(deployerKey);
+        token = new MyERC1155(TOKEN_URI);
+        vm.stopBroadcast();
+
+        console.log("MyERC1155 deployed to:", address(token));
+    }
+}

cronos-contract-boilerplate/foundry/script/MyERC20.s.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.28;
+
+import {Script, console} from "forge-std/Script.sol";
+import {MyERC20} from "../src/MyERC20.sol";
+
+// Deploy with:
+// forge script script/MyERC20.s.sol:MyERC20Script --rpc-url cronos_testnet --broadcast
+contract MyERC20Script is Script {
+    function run() external returns (MyERC20 token) {
+        uint256 deployerKey = vm.envUint("PRIVATE_KEY");
+
+        vm.startBroadcast(deployerKey);
+        token = new MyERC20("My token name", "My token symbol");
+        vm.stopBroadcast();
+
+        console.log("MyERC20 deployed to:", address(token));
+    }
+}

cronos-contract-boilerplate/foundry/script/MyERC721.s.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.28;
+
+import {Script, console} from "forge-std/Script.sol";
+import {MyERC721} from "../src/MyERC721.sol";
+
+// Deploy with:
+// forge script script/MyERC721.s.sol:MyERC721Script --rpc-url cronos_testnet --broadcast
+contract MyERC721Script is Script {
+    function run() external returns (MyERC721 token) {
+        uint256 deployerKey = vm.envUint("PRIVATE_KEY");
+
+        vm.startBroadcast(deployerKey);
+        // MyERC721 constructor takes no arguments
+        token = new MyERC721();
+        vm.stopBroadcast();
+
+        console.log("MyERC721 deployed to:", address(token));
+    }
+}

cronos-contract-boilerplate/foundry/src/MyERC1155.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.28;
+
+import "@openzeppelin/contracts/token/ERC1155/ERC1155.sol";
+import "@openzeppelin/contracts/token/ERC1155/extensions/ERC1155Burnable.sol";
+import "@openzeppelin/contracts/token/ERC1155/extensions/ERC1155Pausable.sol";
+import "@openzeppelin/contracts/token/ERC1155/extensions/ERC1155Supply.sol";
+import "@openzeppelin/contracts/access/AccessControl.sol";
+import "@openzeppelin/contracts/access/Ownable.sol";
+
+contract MyERC1155 is
+    ERC1155,
+    ERC1155Burnable,
+    ERC1155Pausable,
+    ERC1155Supply,
+    AccessControl,
+    Ownable
+{
+    bytes32 public constant CONTROLLER_ROLE = keccak256("CONTROLLER_ROLE");
+    bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
+
+    constructor(string memory uri) ERC1155(uri) Ownable(_msgSender()) {
+        _grantRole(DEFAULT_ADMIN_ROLE, _msgSender());
+        _grantRole(CONTROLLER_ROLE, _msgSender());
+        _grantRole(MINTER_ROLE, _msgSender());
+    }
+
+    function getControllerRole() public view virtual returns (bytes32) {
+        return CONTROLLER_ROLE;
+    }
+
+    function getMinterRole() public view virtual returns (bytes32) {
+        return MINTER_ROLE;
+    }
+
+    function setURI(string memory newuri) public onlyRole(CONTROLLER_ROLE) {
+        _setURI(newuri);
+    }
+
+    function mint(
+        address to,
+        uint256 id,
+        uint256 amount,
+        bytes memory data
+    ) public onlyRole(MINTER_ROLE) {
+        _mint(to, id, amount, data);
+    }
+
+    function mintBatch(
+        address to,
+        uint256[] memory ids,
+        uint256[] memory amounts,
+        bytes memory data
+    ) public onlyRole(MINTER_ROLE) {
+        _mintBatch(to, ids, amounts, data);
+    }
+
+    function pause() public onlyRole(CONTROLLER_ROLE) {
+        _pause();
+    }
+
+    function unpause() public onlyRole(CONTROLLER_ROLE) {
+        _unpause();
+    }
+
+    // The following functions are overrides required by Solidity.
+
+    function _update(
+        address from,
+        address to,
+        uint256[] memory ids,
+        uint256[] memory values
+    ) internal override(ERC1155, ERC1155Pausable, ERC1155Supply) {
+        super._update(from, to, ids, values);
+    }
+
+    function supportsInterface(
+        bytes4 interfaceId
+    ) public view override(ERC1155, AccessControl) returns (bool) {
+        return super.supportsInterface(interfaceId);
+    }
+}