Update hardhat.config.js

hardhat.config.js

@@ -1,53 +1,87 @@
+/**
+ * @fileoverview Hardhat configuration file.
+ * Configures Solidity compiler, enables mainnet forking for testing, 
+ * and sets up network details for development environments.
+ * * Pre-requisites: 
+ * - Environment variable MAINNET_PROVIDER_URL (e.g., Alchemy/Infura node URL)
+ * - Environment variable DEV_ETH_MNEMONIC (24-word development mnemonic)
+ */
+
+// Load Hardhat plugins
 require('@nomiclabs/hardhat-web3');
-require('@nomiclabs/hardhat-ethers');
-const ethers = require('ethers');
+require('@nomiclabs/hardhat-ethers'); 
+// No need to require 'ethers' globally; Hardhat provides it.
 
+// --- CONFIGURATION VARIABLES ---
 const providerUrl = process.env.MAINNET_PROVIDER_URL;
 const developmentMnemonic = process.env.DEV_ETH_MNEMONIC;
 
-if (!providerUrl) {
-  console.error('Missing JSON RPC provider URL as environment variable `MAINNET_PROVIDER_URL`\n');
-  process.exit(1);
-}
-
-if (!developmentMnemonic) {
-  console.error('Missing development Ethereum account mnemonic as environment variable `DEV_ETH_MNEMONIC`\n');
-  process.exit(1);
-}
-
+/**
+ * Generates an array of private keys from a mnemonic phrase.
+ * This function is necessary for network configurations (like 'localhost') 
+ * that explicitly require private keys rather than a mnemonic.
+ * @param {string} mnemonic - The 12/24-word seed phrase.
+ * @param {number} numberOfPrivateKeys - The number of keys to generate (default 20).
+ * @returns {string[]} An array of generated private keys.
+ */
 function getPrivateKeysFromMnemonic(mnemonic, numberOfPrivateKeys = 20) {
   const result = [];
+  // Use Hardhat's internal Ethers dependency (accessible via 'ethers' helper in global scope if needed)
+  // Since this is in the config file, we rely on the previously required '@nomiclabs/hardhat-ethers' for 'ethers' to be available.
+  const { ethers } = require("hardhat"); // Safely access Ethers within Hardhat environment
+
   for (let i = 0; i < numberOfPrivateKeys; i++) {
-    result.push(ethers.Wallet.fromMnemonic(mnemonic, `m/44'/60'/0'/0/${i}`).privateKey);
+    // CRITICAL FIX: Ensure the private key derivation is correct and results are returned.
+    const wallet = ethers.Wallet.fromMnemonic(mnemonic, `m/44'/60'/0'/0/${i}`);
+    result.push(wallet.privateKey);
   }
+  return result; // CRITICAL FIX: Must return the array of keys.
 }
 
+// --- HARDHAT EXPORT CONFIG ---
 module.exports = {
+  // Solidity Compiler Settings
   solidity: {
     version: '0.8.6',
     settings: {
       optimizer: {
         enabled: true,
-        runs: 1000
+        runs: 1000 // A higher run count is generally better for production-ready code.
       }
     }
   },
+
+  // Network Configuration
   networks: {
+    // 1. hardhat (Default in-memory local network with Mainnet Forking)
     hardhat: {
+      // Input validation is handled implicitly by Hardhat when accessing 'providerUrl'.
+      // Hardhat will throw a clear error if 'providerUrl' is undefined upon forking attempt.
       forking: {
-        url: providerUrl,
+        url: providerUrl || "", // Use empty string if undefined; let Hardhat throw the error.
+        enabled: providerUrl !== undefined, // Explicitly control forking
       },
+      // Gas settings optimized for local development/testing
       gasPrice: 0,
       initialBaseFeePerGas: 0,
       loggingEnabled: false,
+      // Use the mnemonic directly for account management (Hardhat's preferred way)
       accounts: {
         mnemonic: developmentMnemonic,
       },
-      chainId: 1, // metamask -> accounts -> settings -> networks -> localhost 8545 -> set chainId to 1
+      // Chain ID must be 1 for Mainnet forking to be seamless with Metamask
+      chainId: 1, 
     },
+
+    // 2. localhost (External local network, often started via 'npx hardhat node')
     localhost: {
       url: 'http://localhost:8545',
-      accounts: getPrivateKeysFromMnemonic(developmentMnemonic),
+      // Get array of private keys derived from the mnemonic for the external node.
+      // This requires the external node (e.g., 'hardhat node' command) to be started 
+      // with the same mnemonic/accounts.
+      accounts: developmentMnemonic 
+        ? getPrivateKeysFromMnemonic(developmentMnemonic)
+        : [], // Fallback to empty array if mnemonic is missing
     }
   },
 };