chore: example the mocha tutorial with a script running against optimism

A `base` network has been added to the `hardhat.config.ts` and a simple
deployment script added that runs against the Base network.

v-next/hardhat/templates/mocha-ethers/README.md

@@ -4,7 +4,16 @@
 
 > NOTE: There are several plugins from the Hardhat toolbox that have not been ported to Hardhat v3 yet. In testing terms, the biggest ommision is `hardhat-chai-matchers`.
 
-This project demonstrates basic Hardhat usecases within a TypeScript project. It comes with a minimal Hardhat configuration file and both JS/TS integration tests and Solidity Tests.
+This project demonstrates basic Hardhat usecases within a TypeScript project. It comes with:
+
+* a minimal Hardhat configuration file
+* JS/TS integration tests
+* Solidity Tests
+* A script demonstrating how to deploy a contract to an in-memory Hardhat node simulating Base (an Optimism l2 chain)
+
+## Usage
+
+### Testing
 
 For integration testing it uses the Mocha test runner and the Ethers.js library for interacting with Ethereum nodes.
 
@@ -15,3 +24,13 @@ Try running the following commands to see Hardhat in action:
 # and the Solidity Test suite
 npx hardhat3 test
 ```
+
+Hardhat v3 comes with support for simulating chains other than Ethereum l1. To deploy against an
+
+### Multi-chain support
+
+To deploy a contract to an in-memory Hardhat node simulating Base (an Optimism l2 chain), run:
+
+```shell
+npx hardhat3 run scripts/deploy-counter-contract.ts
+```

v-next/hardhat/templates/mocha-ethers/hardhat.config.ts

@@ -7,6 +7,17 @@ import HardhatNetworkHelpers from "@ignored/hardhat-vnext-network-helpers";
 const config: HardhatUserConfig = {
   plugins: [HardhatMochaTestRunner, HardhatEthers, HardhatNetworkHelpers],
   solidity: "0.8.24",
+  defaultNetwork: "hardhat",
+  networks: {
+    "local-base": {
+      chainId: 8453,
+      type: "edr",
+      chainType: "optimism",
+      gas: "auto",
+      gasPrice: "auto",
+      gasMultiplier: 1,
+    },
+  },
 };
 
 export default config;

v-next/hardhat/templates/mocha-ethers/scripts/deploy-counter-contract.ts

@@ -0,0 +1,11 @@
+import hre from "@ignored/hardhat-vnext";
+
+async function deployCounterContract() {
+  const optimism = await hre.network.connect("local-base", "optimism");
+
+  const contract = await optimism.ethers.deployContract("Counter");
+
+  console.log("Counter contract address:", await contract.getAddress());
+}
+
+deployCounterContract();