Update dependencies and scripts. Also added a test file.

contracts/BuyMeACoffee.sol

@@ -11,18 +11,18 @@ contract BuyMeACoffee {
         string name,
         string message
     );
-    
+
     // Memo struct.
     struct Memo {
         address from;
         uint256 timestamp;
         string name;
         string message;
     }
-    
+
     // Address of contract deployer. Marked payable so that
     // we can withdraw to this address later.
-    address payable owner;
+    address payable public owner;
 
     // List of all memos received from coffee purchases.
     Memo[] memos;
@@ -45,25 +45,18 @@ contract BuyMeACoffee {
      * @param _name name of the coffee purchaser
      * @param _message a nice message from the purchaser
      */
-    function buyCoffee(string memory _name, string memory _message) public payable {
+    function buyCoffee(
+        string memory _name,
+        string memory _message
+    ) public payable {
         // Must accept more than 0 ETH for a coffee.
         require(msg.value > 0, "can't buy coffee for free!");
 
         // Add the memo to storage!
-        memos.push(Memo(
-            msg.sender,
-            block.timestamp,
-            _name,
-            _message
-        ));
+        memos.push(Memo(msg.sender, block.timestamp, _name, _message));
 
         // Emit a NewMemo event with details about the memo.
-        emit NewMemo(
-            msg.sender,
-            block.timestamp,
-            _name,
-            _message
-        );
+        emit NewMemo(msg.sender, block.timestamp, _name, _message);
     }
 
     /**

hardhat.config.js

@@ -1,22 +1,35 @@
-require("@nomiclabs/hardhat-ethers");
-require("@nomiclabs/hardhat-waffle");
-require("dotenv").config()
+// This is essential to have global access to ethers.js
+require('@nomicfoundation/hardhat-toolbox');
+require('dotenv').config();
 
 // You need to export an object to set up your config
 // Go to https://hardhat.org/config/ to learn more
 
 const GOERLI_URL = process.env.GOERLI_URL;
+const SEPOLIA_URL = process.env.SEPOLIA_URL;
+const POLYGONZK_URL = process.env.POLYGONZK_URL;
 const PRIVATE_KEY = process.env.PRIVATE_KEY;
 
 /**
  * @type import('hardhat/config').HardhatUserConfig
  */
 module.exports = {
-  solidity: "0.8.4",
+  solidity: '0.8.24',
   networks: {
     goerli: {
+      networkCheckTimeout: 10000,
       url: GOERLI_URL,
-      accounts: [PRIVATE_KEY]
-    }
-  }
+      accounts: [PRIVATE_KEY],
+    },
+    sepolia: {
+      networkCheckTimeout: 10000,
+      url: SEPOLIA_URL,
+      accounts: [PRIVATE_KEY],
+    },
+    polygonZk: {
+      networkCheckTimeout: 10000,
+      url: POLYGONZK_URL,
+      accounts: [PRIVATE_KEY],
+    },
+  },
 };