From 19efa7a166b3a98299a895481a39e7356db26184 Mon Sep 17 00:00:00 2001
From: Benjamin Smith <bh2smith@users.noreply.github.com>
Date: Tue, 12 Nov 2024 20:56:46 +0100
Subject: [PATCH] Transaction Serializable & RlpHex Guards

---
 src/types/guards.ts             | 30 +++++++++++++-
 tests/unit/types.guards.test.ts | 70 ++++++++++++++++++++++++++++++++-
 2 files changed, 98 insertions(+), 2 deletions(-)

diff --git a/src/types/guards.ts b/src/types/guards.ts
index d59cf5e..1275ce0 100644
--- a/src/types/guards.ts
+++ b/src/types/guards.ts
@@ -1,4 +1,11 @@
-import { isAddress, TypedDataDomain } from "viem";
+import {
+  Hex,
+  isAddress,
+  parseTransaction,
+  serializeTransaction,
+  TransactionSerializable,
+  TypedDataDomain,
+} from "viem";
 import { EIP712TypedData, SignMethod, TypedMessageTypes } from ".";
 
 export function isSignMethod(method: unknown): method is SignMethod {
@@ -76,3 +83,24 @@ export const isEIP712TypedData = (obj: unknown): obj is EIP712TypedData => {
     typeof candidate.primaryType === "string"
   );
 };
+
+// Cheeky attempt to serialize. return true if successful!
+export function isTransactionSerializable(
+  data: unknown
+): data is TransactionSerializable {
+  try {
+    serializeTransaction(data as TransactionSerializable);
+    return true;
+  } catch (error) {
+    return false;
+  }
+}
+
+export function isRlpHex(data: unknown): data is Hex {
+  try {
+    parseTransaction(data as Hex);
+    return true;
+  } catch (error) {
+    return false;
+  }
+}
diff --git a/tests/unit/types.guards.test.ts b/tests/unit/types.guards.test.ts
index 83bf562..d334331 100644
--- a/tests/unit/types.guards.test.ts
+++ b/tests/unit/types.guards.test.ts
@@ -1,4 +1,17 @@
-import { isEIP712TypedData, isSignMethod } from "../../src/";
+import { TransactionSerializable } from "viem";
+import {
+  isEIP712TypedData,
+  isRlpHex,
+  isSignMethod,
+  isTransactionSerializable,
+} from "../../src/";
+
+const validEIP1559Transaction: TransactionSerializable = {
+  to: "0x70997970C51812dc3A010C7d01b50e0d17dc79C8",
+  value: BigInt(1000000000000000000), // 1 ETH
+  chainId: 1,
+  maxFeePerGas: 1n,
+};
 describe("Type Guards", () => {
   it("isSignMethod", async () => {
     expect(isSignMethod("poop")).toBe(false);
@@ -52,3 +65,58 @@ describe("Type Guards", () => {
     expect(isEIP712TypedData(typedData)).toBe(true);
   });
 });
+
+describe("isTransactionSerializable", () => {
+  it("should return true for valid transaction data", () => {
+    expect(isTransactionSerializable(validEIP1559Transaction)).toBe(true);
+  });
+
+  it("should return false for invalid transaction data", () => {
+    const invalidCases = [
+      null,
+      undefined,
+      {},
+      { to: "invalid-address" },
+      { value: "not-a-bigint" },
+      { chainId: "not-a-number" },
+      "random string",
+      123,
+      [],
+    ];
+
+    invalidCases.forEach((testCase) => {
+      expect(isTransactionSerializable(testCase)).toBe(false);
+    });
+  });
+});
+
+describe("isRlpHex", () => {
+  it("should return true for valid RLP-encoded transaction hex", () => {
+    // This is an example of a valid RLP-encoded transaction hex:
+
+    // serializeTransaction(validEIP1559Transaction)
+    const validRlpHex =
+      "0x02e501808001809470997970c51812dc3a010c7d01b50e0d17dc79c8880de0b6b3a764000080c0";
+    expect(isRlpHex(validRlpHex)).toBe(true);
+  });
+
+  it("should return false for invalid RLP hex data", () => {
+    const invalidCases = [
+      null,
+      undefined,
+      {},
+      "not-a-hex",
+      "0x", // empty hex
+      "0x1234", // too short
+      "0xinvalid",
+      123,
+      [],
+      // Invalid RLP structure but valid hex
+      "0x1234567890abcdef",
+    ];
+
+    invalidCases.forEach((testCase) => {
+      expect(isRlpHex(testCase)).toBe(false);
+    });
+  });
+});