I've updated the Inbox section for new people doing the course.

inbox/.env

@@ -0,0 +1,3 @@
+RPC_URL="https://rinkeby.infura.io/v3/YOUR_API_KEY"
+PRIVATE_KEY="YOUR_PRIVATE_KEY_STARTING_WITH_0x"
+ACCOUNT="YOUR_ACCOUNT"

inbox/README.md

@@ -0,0 +1,7 @@
+First of all, open a terminal at the root folder and run "npm i".
+
+BEFORE running the tests or using the command "node compile":
+Open the ".env" file and replace the values:
+* RPC_URL - Get it for the testnet you want to use from your infura.io account.
+* ACCOUNT - Open Metamask and by clicking on e.g. "Account 1", you will copy the value to the clipboard.
+* PRIVATE_KEY - Open Metamask, click the 3 dots next to "Account 1" -> Account details -> Export Private Key. You will get your key after typing your password. Paste it in this field in .env but prefix the copied value with "0x", e.g. "0xbe1e21dasd21ds...."

inbox/compile.js

@@ -3,6 +3,24 @@ const fs = require('fs');
 const solc = require('solc');
 
 const inboxPath = path.resolve(__dirname, 'contracts', 'Inbox.sol');
-const source = fs.readFileSync(inboxPath, 'utf8');
 
-module.exports = solc.compile(source, 1).contracts[':Inbox'];
+var input = {
+    language: 'Solidity',
+    sources: {
+      'Inbox.sol': {
+        content: fs.readFileSync(inboxPath, 'utf8')
+      }
+    },
+    settings: {
+      outputSelection: {
+        '*': {
+          '*': ['*']
+        }
+      }
+    }
+  };
+
+  var output = JSON.parse(solc.compile(JSON.stringify(input)));
+  //console.log(output.contracts['Inbox.sol']['Inbox'].abi);
+  //console.log(output.contracts['Inbox.sol']['Inbox']['evm'].bytecode); to get bytecode
+  module.exports = output.contracts['Inbox.sol']['Inbox'];

inbox/contracts/Inbox.sol

@@ -1,13 +1,15 @@
-pragma solidity ^0.4.17;
+// SPDX-License-Identifier: CPL-1.0
+
+pragma solidity 0.8.0;
 
 contract Inbox {
     string public message;
-
-    function Inbox(string initialMessage) public {
+    
+    constructor (string memory initialMessage) {
         message = initialMessage;
     }
 
-    function setMessage(string newMessage) public {
+    function setMessage (string calldata newMessage) public {
         message = newMessage;
     }
-}
+}

inbox/deploy.js

@@ -1,22 +1,21 @@
-const HDWalletProvider = require('truffle-hdwallet-provider');
+require('dotenv').config()
+const HDWalletProvider = require('@truffle/hdwallet-provider')
 const Web3 = require('web3');
-const { interface, bytecode } = require('./compile');
+const abi = require('./compile').abi; // the contract interface aka ABI
+const bytecode = require('./compile').evm.bytecode.object;
 
-const provider = new HDWalletProvider(
-  'call glow acoustic vintage front ring trade assist shuffle mimic volume reject',
-  'https://rinkeby.infura.io/orDImgKRzwNrVCDrAk5Q'
-);
+const provider = new HDWalletProvider(process.env.PRIVATE_KEY, process.env.RPC_URL)
 const web3 = new Web3(provider);
 
 const deploy = async () => {
-  const accounts = await web3.eth.getAccounts();
+    const accounts = await web3.eth.getAccounts();
+    console.log('Attempting to deploy from account', accounts[0]);
 
-  console.log('Attempting to deploy from account', accounts[0]);
+    const result = await new web3.eth.Contract(abi)
+    .deploy({data: bytecode, arguments: ['Hi there!']})
+    .send({from: accounts[0]});
 
-  const result = await new web3.eth.Contract(JSON.parse(interface))
-    .deploy({ data: bytecode, arguments: ['Hi there!'] })
-    .send({ gas: '1000000', from: accounts[0] });
-
-  console.log('Contract deployed to', result.options.address);
+    console.log('Contract deployed to: ', result.options.address);
 };
-deploy();
+
+deploy();