From eedc99cc95df30dc673a1cbe17af658a2bca3df3 Mon Sep 17 00:00:00 2001
From: mouseless <97399882+mouseless-eth@users.noreply.github.com>
Date: Thu, 15 May 2025 07:57:12 +0100
Subject: [PATCH] Add getChain helper to remove foundry chain hardcode

---
 .changeset/bitter-berries-exist.md            |  5 +++
 .../mock-paymaster/helpers/erc20-utils.ts     |  7 ++-
 packages/mock-paymaster/helpers/utils.ts      | 44 ++++++++++++++-----
 packages/mock-paymaster/index.ts              |  9 ++--
 4 files changed, 47 insertions(+), 18 deletions(-)
 create mode 100644 .changeset/bitter-berries-exist.md

diff --git a/.changeset/bitter-berries-exist.md b/.changeset/bitter-berries-exist.md
new file mode 100644
index 00000000..2986ba6e
--- /dev/null
+++ b/.changeset/bitter-berries-exist.md
@@ -0,0 +1,5 @@
+---
+"@pimlico/mock-paymaster": patch
+---
+
+Remove foundry chain hardcode by introducing getChain helper
diff --git a/packages/mock-paymaster/helpers/erc20-utils.ts b/packages/mock-paymaster/helpers/erc20-utils.ts
index c09a4540..f2ad57bf 100644
--- a/packages/mock-paymaster/helpers/erc20-utils.ts
+++ b/packages/mock-paymaster/helpers/erc20-utils.ts
@@ -36,7 +36,7 @@ export const deployErc20Token = async (
 }
 
 export const tokenBalanceOf = async (holder: Address, anvilRpc: string) => {
-    const publicClient = getPublicClient(anvilRpc)
+    const publicClient = await getPublicClient(anvilRpc)
 
     const balance = await publicClient.call({
         to: erc20Address,
@@ -59,7 +59,10 @@ export const sudoMintTokens = async ({
     to: Address
     anvilRpc: string
 }) => {
-    const walletClient = getAnvilWalletClient({ addressIndex: 0, anvilRpc })
+    const walletClient = await getAnvilWalletClient({
+        addressIndex: 0,
+        anvilRpc
+    })
 
     await walletClient.sendTransaction({
         to: erc20Address,
diff --git a/packages/mock-paymaster/helpers/utils.ts b/packages/mock-paymaster/helpers/utils.ts
index 2b4b3f68..13c11265 100644
--- a/packages/mock-paymaster/helpers/utils.ts
+++ b/packages/mock-paymaster/helpers/utils.ts
@@ -7,10 +7,10 @@ import {
     type Transport,
     type WalletClient,
     createPublicClient,
-    createWalletClient
+    createWalletClient,
+    defineChain
 } from "viem"
 import { mnemonicToAccount } from "viem/accounts"
-import { foundry } from "viem/chains"
 import { erc20Address } from "./erc20-utils.js"
 import { RpcError, ValidationErrors } from "./schema.js"
 
@@ -19,9 +19,33 @@ export const maxBigInt = (a: bigint, b: bigint) => {
     return a > b ? a : b
 }
 
-export const getPublicClient = (
+export const getChain = async (anvilRpc: string) => {
+    const tempClient = createPublicClient({
+        transport: http(anvilRpc)
+    })
+
+    const chain = defineChain({
+        id: await tempClient.getChainId(),
+        name: "chain",
+        nativeCurrency: {
+            name: "ETH",
+            symbol: "ETH",
+            decimals: 18
+        },
+        rpcUrls: {
+            default: {
+                http: [],
+                webSocket: undefined
+            }
+        }
+    })
+
+    return chain
+}
+
+export const getPublicClient = async (
     anvilRpc: string
-): PublicClient<Transport, Chain> => {
+): Promise<PublicClient<Transport, Chain>> => {
     const transport = http(anvilRpc, {
         // onFetchRequest: async (req) => {
         //     console.log(await req.json(), "request")
@@ -32,19 +56,17 @@ export const getPublicClient = (
     })
 
     return createPublicClient({
-        chain: foundry,
+        chain: await getChain(anvilRpc),
         transport: transport,
         pollingInterval: 100
     })
 }
 
-export const getAnvilWalletClient = ({
+export const getAnvilWalletClient = async ({
     addressIndex,
     anvilRpc
-}: { addressIndex: number; anvilRpc: string }): WalletClient<
-    Transport,
-    Chain,
-    Account
+}: { addressIndex: number; anvilRpc: string }): Promise<
+    WalletClient<Transport, Chain, Account>
 > => {
     return createWalletClient({
         account: mnemonicToAccount(
@@ -53,7 +75,7 @@ export const getAnvilWalletClient = ({
                 addressIndex
             }
         ),
-        chain: foundry,
+        chain: await getChain(anvilRpc),
         transport: http(anvilRpc)
     })
 }
diff --git a/packages/mock-paymaster/index.ts b/packages/mock-paymaster/index.ts
index 14450e14..9ead333b 100644
--- a/packages/mock-paymaster/index.ts
+++ b/packages/mock-paymaster/index.ts
@@ -3,9 +3,8 @@ import Fastify from "fastify"
 import { defineInstance } from "prool"
 import { http, createPublicClient } from "viem"
 import { createBundlerClient } from "viem/account-abstraction"
-import { foundry } from "viem/chains"
 import { deployErc20Token } from "./helpers/erc20-utils.js"
-import { getAnvilWalletClient } from "./helpers/utils.js"
+import { getAnvilWalletClient, getChain } from "./helpers/utils.js"
 import { createRpcHandler } from "./relay.js"
 import { deployPaymasters } from "./singletonPaymasters.js"
 
@@ -23,16 +22,16 @@ export const paymaster = defineInstance(
             port: _port,
             name: "mock-paymaster",
             start: async ({ port = _port }) => {
-                const walletClient = getAnvilWalletClient({
+                const walletClient = await getAnvilWalletClient({
                     anvilRpc,
                     addressIndex: 1
                 })
                 const publicClient = createPublicClient({
                     transport: http(anvilRpc),
-                    chain: foundry
+                    chain: await getChain(anvilRpc)
                 })
                 const bundler = createBundlerClient({
-                    chain: foundry,
+                    chain: await getChain(anvilRpc),
                     transport: http(altoRpc)
                 })