Add sign cheque script

scripts/sign-cheque.js

@@ -0,0 +1,69 @@
+const hre = require("hardhat");
+const eip712 = require("ethers-eip712");
+
+const EIP712Domain = [
+    { name: 'name', type: 'string' },
+    { name: 'version', type: 'string' },
+    { name: 'chainId', type: 'uint256' }
+    // Missing
+    // {name: "verifyingContract", type: "address"},
+]
+
+const ChequeType = [
+    { name: 'chequebook', type: 'address' },
+    { name: 'beneficiary', type: 'address' },
+    { name: 'cumulativePayout', type: 'uint256' }
+]
+
+// XXX Hardcoded from recent deploy to Hardhat dev chain
+var erc20address = "0x5FbDB2315678afecb367f032d93F642f64180aa3";
+var aliceAddress = "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266";
+var aliceSwapAddress = "0xCafac3dD18aC6c6e92c921884f9E4176737C052c";
+var bobAddress = "0x70997970C51812dc3A010C7d01b50e0d17dc79C8";
+
+// TODO This should be parameterized with arguments, so probably as a task or standalone script?
+async function main() {
+    var swapAddress = aliceSwapAddress;
+    var beneficiary = bobAddress;
+    var cumulativePayout = 500;
+    var chainId = 31337;
+
+    var signers = await ethers.getSigners();
+    var aliceSigner = signers[0];
+
+    const cheque = {
+        chequebook: swapAddress,
+        beneficiary,
+        cumulativePayout: cumulativePayout
+    };
+
+    console.log("Cheque", cheque);
+
+    const typedData = {
+        types: {
+            EIP712Domain,
+            Cheque: ChequeType
+        },
+        domain: {
+          name: "Chequebook",
+          version: "1.0",
+          chainId
+        },
+        primaryType: 'Cheque',
+        message: cheque
+    }
+
+    const digest = eip712.TypedDataUtils.encodeDigest(typedData)
+    const digestHex = ethers.utils.hexlify(digest)
+
+    // NOTE this may be different from eth_signTypedData_v3, etc
+    const signature = await aliceSigner.signMessage(digest)
+    console.log("Signature:", signature);
+}
+
+main()
+  .then(() => process.exit(0))
+  .catch(error => {
+    console.error(error);
+    process.exit(1);
+  });

scripts/sign-script.js

@@ -1,7 +1,8 @@
+// Example code to test EIP712 library
+
 const hre = require("hardhat");
 const eip712 = require("ethers-eip712");
 
-
 async function main() {
     const typedData = {
         types: {