Transpile 7bce2b72

test/helpers/sign.js

@@ -0,0 +1,47 @@
+function toEthSignedMessageHash (messageHex) {
+  const messageBuffer = Buffer.from(messageHex.substring(2), 'hex');
+  const prefix = Buffer.from(`\u0019Ethereum Signed Message:\n${messageBuffer.length}`);
+  return web3.utils.sha3(Buffer.concat([prefix, messageBuffer]));
+}
+
+/**
+ * Create a signer between a contract and a signer for a voucher of method, args, and redeemer
+ * Note that `method` is the web3 method, not the truffle-contract method
+ * @param contract TruffleContract
+ * @param signer address
+ * @param redeemer address
+ * @param methodName string
+ * @param methodArgs any[]
+ */
+const getSignFor = (contract, signer) => (redeemer, methodName, methodArgs = []) => {
+  const parts = [
+    contract.address,
+    redeemer,
+  ];
+
+  const REAL_SIGNATURE_SIZE = 2 * 65; // 65 bytes in hexadecimal string length
+  const PADDED_SIGNATURE_SIZE = 2 * 96; // 96 bytes in hexadecimal string length
+  const DUMMY_SIGNATURE = `0x${web3.utils.padLeft('', REAL_SIGNATURE_SIZE)}`;
+
+  // if we have a method, add it to the parts that we're signing
+  if (methodName) {
+    if (methodArgs.length > 0) {
+      parts.push(
+        contract.contract.methods[methodName](...methodArgs.concat([DUMMY_SIGNATURE])).encodeABI()
+          .slice(0, -1 * PADDED_SIGNATURE_SIZE),
+      );
+    } else {
+      const abi = contract.abi.find(abi => abi.name === methodName);
+      parts.push(abi.signature);
+    }
+  }
+
+  // return the signature of the "Ethereum Signed Message" hash of the hash of `parts`
+  const messageHex = web3.utils.soliditySha3(...parts);
+  return web3.eth.sign(messageHex, signer);
+};
+
+module.exports = {
+  toEthSignedMessageHash,
+  getSignFor,
+};