docs: add hardhat example + ci (ethereum-optimism#641)

* feat(hardhat-ovm): allow overriding the polling interval for the provider and its signers

The default is 50ms, which should make running the OVM tests smooth. If you want
to run tests against a remote node and do not want to overwhelm it, set the
parameter in the hardhat config's network

* chore: add changeset

* docs: add hardhat example

imported from https://github.com/ethereum-optimism/optimism-tutorial/

* ci: add deploy/deploy:ovm

* fix(contracts): wait for contracts to finish

workaround hardhat not generating build artifacts for both evm and ovm

* fix: use istanbul hard fork

* test(contracts): remove hardcoded post-state in nuisance gas test

this post state is not giving us much info, and it's hard to
update it or debug it when it does not pass for any reason

Co-authored-by: Georgios Konstantopoulos <[email protected]>

.changeset/chatty-clouds-melt.md

@@ -0,0 +1,5 @@
+---
+"@eth-optimism/hardhat-ovm": minor
+---
+
+allow overriding the ethers polling interval

.github/workflows/integration.yml

@@ -15,6 +15,7 @@ jobs:
         DOCKER_BUILDKIT: 1
         COMPOSE_DOCKER_CLI_BUILD: 1
     steps:
+      # Monorepo tests
       - uses: actions/checkout@v2
 
       - name: Get yarn cache directory path
@@ -46,5 +47,19 @@ jobs:
         env:
           FORCE_COLOR: 1
           ENABLE_GAS_REPORT: 1
+
       - name: Print gas report
         run: cat integration-tests/gas-report.txt
+
+      # Examples Tests
+      - name: Test & deploy hardhat-example on hardhat (regression)
+        working-directory: ./examples/hardhat
+        run: |
+          yarn deploy
+          yarn test
+
+      - name: Test & deploy hardhat-example on Optimism
+        working-directory: ./examples/hardhat
+        run: |
+          yarn deploy:ovm
+          yarn test:ovm

examples/hardhat/README.md

@@ -0,0 +1,6 @@
+# The Official™ Optimism Tutorial
+
+[![Discord](https://img.shields.io/discord/667044843901681675.svg?color=768AD4&label=discord&logo=https%3A%2F%2Fdiscordapp.com%2Fassets%2F8c9701b98ad4372b58f13fd9f65f966e.svg)](https://discord.com/channels/667044843901681675)
+[![Twitter Follow](https://img.shields.io/twitter/follow/optimismPBC.svg?label=optimismPBC&style=social)](https://twitter.com/optimismPBC)
+
+### For the full README, please see the [guided repository of the `optimism-tutorial`](https://github.com/ethereum-optimism/optimism-tutorial) repository

examples/hardhat/contracts/ERC20.sol

@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >0.6.0 <0.8.0;
+
+/**
+ * @title ERC20
+ * @dev A super simple ERC20 implementation!
+ */
+contract ERC20 {
+
+    /**********
+     * Events *
+     **********/
+
+    event Transfer(
+        address indexed _from,
+        address indexed _to,
+        uint256 _value
+    );
+
+    event Approval(
+        address indexed _owner,
+        address indexed _spender,
+        uint256 _value
+    );
+
+
+    /*************
+     * Variables *
+     *************/
+
+    mapping (address => uint256) public balances;
+    mapping (address => mapping (address => uint256)) public allowances;
+
+    // Some optional extra goodies.
+    uint256 public totalSupply;
+    string public name;
+
+
+    /***************
+     * Constructor *
+     ***************/
+
+    /**
+     * @param _initialSupply Initial maximum token supply.
+     * @param _name A name for our ERC20 (technically optional, but it's fun ok jeez).
+     */
+    constructor(
+        uint256 _initialSupply,
+        string memory _name
+    )
+        public
+    {
+        balances[msg.sender] = _initialSupply;
+        totalSupply = _initialSupply;
+        name = _name;
+    }
+
+
+    /********************
+     * Public Functions *
+     ********************/
+
+    /**
+     * Checks the balance of an address.
+     * @param _owner Address to check a balance for.
+     * @return Balance of the address.
+     */
+    function balanceOf(
+        address _owner
+    )
+        external
+        view
+        returns (
+            uint256
+        )
+    {
+        return balances[_owner];
+    }
+
+    /**
+     * Transfers a balance from your account to someone else's account!
+     * @param _to Address to transfer a balance to.
+     * @param _amount Amount to transfer to the other account.
+     * @return true if the transfer was successful.
+     */
+    function transfer(
+        address _to,
+        uint256 _amount
+    )
+        external
+        returns (
+            bool
+        )
+    {
+        require(
+            balances[msg.sender] >= _amount,
+            "You don't have enough balance to make this transfer!"
+        );
+
+        balances[msg.sender] -= _amount;
+        balances[_to] += _amount;
+
+        emit Transfer(
+            msg.sender,
+            _to,
+            _amount
+        );
+
+        return true;
+    }
+
+    /**
+     * Transfers a balance from someone else's account to another account. You need an allowance
+     * from the sending account for this to work!
+     * @param _from Account to transfer a balance from.
+     * @param _to Account to transfer a balance to.
+     * @param _amount Amount to transfer to the other account.
+     * @return true if the transfer was successful.
+     */
+    function transferFrom(
+        address _from,
+        address _to,
+        uint256 _amount
+    )
+        external
+        returns (
+            bool
+        )
+    {
+        require(
+            balances[_from] >= _amount,
+            "Can't transfer from the desired account because it doesn't have enough balance."
+        );
+
+        require(
+            allowances[_from][msg.sender] >= _amount,
+            "Can't transfer from the desired account because you don't have enough of an allowance."
+        );
+
+        balances[_to] += _amount;
+        balances[_from] -= _amount;
+
+        emit Transfer(
+            _from,
+            _to,
+            _amount
+        );
+
+        return true;
+    }
+
+    /**
+     * Approves an account to spend some amount from your account.
+     * @param _spender Account to approve a balance for.
+     * @param _amount Amount to allow the account to spend from your account.
+     * @return true if the allowance was successful.
+     */
+    function approve(
+        address _spender,
+        uint256 _amount
+    )
+        external
+        returns (
+            bool
+        )
+    {
+        allowances[msg.sender][_spender] = _amount;
+
+        emit Approval(
+            msg.sender,
+            _spender,
+            _amount
+        );
+
+        return true;
+    }
+
+    /**
+     * Checks how much a given account is allowed to spend from another given account.
+     * @param _owner Address of the account to check an allowance from.
+     * @param _spender Address of the account trying to spend from the owner.
+     * @return Allowance for the spender from the owner.
+     */
+    function allowance(
+        address _owner,
+        address _spender
+    )
+        external
+        view
+        returns (
+            uint256
+        )
+    {
+        return allowances[_owner][_spender];
+    }
+}

examples/hardhat/deploy/ERC20.deploy.js

@@ -0,0 +1,20 @@
+// Just a standard hardhat-deploy deployment definition file!
+const func = async (hre) => {
+  const { deployments, getNamedAccounts } = hre
+  const { deploy } = deployments
+  const { deployer } = await getNamedAccounts()
+
+  const initialSupply = 1000000
+  const name = 'My Optimistic Token'
+
+  await deploy('ERC20', {
+    from: deployer,
+    args: [initialSupply, name],
+    gasPrice: hre.ethers.BigNumber.from('0'),
+    gasLimit: 8999999,
+    log: true
+  })
+}
+
+func.tags = ['ERC20']
+module.exports = func

examples/hardhat/hardhat.config.js

@@ -0,0 +1,29 @@
+require('@nomiclabs/hardhat-ethers')
+require('@nomiclabs/hardhat-waffle')
+require('hardhat-deploy')
+require("@eth-optimism/hardhat-ovm")
+
+module.exports = {
+  networks: {
+    // Add this network to your config!
+    optimism: {
+      url: 'http://127.0.0.1:8545',
+      // instantiate with a mnemonic so that you have >1 accounts available
+      accounts: {
+        mnemonic: 'test test test test test test test test test test test junk'
+      },
+      // This sets the gas price to 0 for all transactions on L2. We do this
+      // because account balances are not automatically initiated with an ETH
+      // balance (yet, sorry!).
+      gasPrice: 0,
+      ovm: true // This sets the network as using the ovm and ensure contract will be compiled against that.
+    },
+  },
+  solidity: '0.7.6',
+  ovm: {
+    solcVersion: '0.7.6'
+  },
+  namedAccounts: {
+    deployer: 0
+  },
+}

examples/hardhat/package.json

@@ -0,0 +1,28 @@
+{
+  "name": "@eth-optimism/hardhat-example",
+  "private": true,
+  "version": "1.0.0",
+  "main": "index.js",
+  "license": "MIT",
+  "scripts": {
+    "deploy": "hardhat deploy",
+    "deploy:ovm": "hardhat deploy --network optimism",
+    "compile": "hardhat compile",
+    "compile:ovm": "hardhat compile --network optimism",
+    "test": "hardhat test",
+    "test:ovm": "hardhat test --network optimism",
+    "clean": "rimraf ./cache-ovm ./cache ./artifacts-ovm ./artifacts ./deployments"
+  },
+  "devDependencies": {
+    "@eth-optimism/hardhat-ovm": "^0.0.3",
+    "@nomiclabs/hardhat-ethers": "^2.0.1",
+    "@nomiclabs/hardhat-waffle": "^2.0.1",
+    "chai": "4.3.4",
+    "chai-as-promised": "^7.1.1",
+    "ethereum-waffle": "^3.3.0",
+    "ethers": "^5.1.4",
+    "hardhat": "^2.2.0",
+    "hardhat-deploy": "^0.7.5",
+    "mocha": "^8.2.1"
+  }
+}