feat: Unblock wallet_switchEthereumChain (#2634)

This removes `wallet_switchEthereumChain` from the `BLOCKED_RPC_METHODS`
list.

Closes MetaMask/MetaMask-planning#2938.
Closes #2654.

Blocked by:

- MetaMask/core#4602

Author: Mrtenz

packages/examples/packages/ethereum-provider/snap.manifest.json

@@ -7,7 +7,7 @@
     "url": "https://github.com/MetaMask/snaps.git"
   },
   "source": {
-    "shasum": "EBjcd8iJ6rPwGXcEmAhWGJWHh/m0RV8X+eid/HIUjEY=",
+    "shasum": "cKFOaKJv2NJ7UOWRzhpP1fIq40SPyjhd1sG42AceRBY=",
     "location": {
       "npm": {
         "filePath": "dist/bundle.js",

packages/examples/packages/ethereum-provider/src/index.ts

@@ -10,7 +10,23 @@ import {
   hexToNumber,
 } from '@metamask/utils';
 
-import type { PersonalSignParams, SignTypedDataParams } from './types';
+import type {
+  BaseParams,
+  PersonalSignParams,
+  SignTypedDataParams,
+} from './types';
+
+/**
+ * Set the active Ethereum chain for the Snap.
+ *
+ * @param chainId - The chain ID to switch to.
+ */
+async function switchChain(chainId: Hex) {
+  await ethereum.request({
+    method: 'wallet_switchEthereumChain',
+    params: [{ chainId }],
+  });
+}
 
 /**
  * Get the current gas price using the `ethereum` global. This is essentially
@@ -207,6 +223,9 @@ async function signTypedData(message: string, from: string) {
  * @see https://docs.metamask.io/snaps/reference/rpc-api/#wallet_invokesnap
  */
 export const onRpcRequest: OnRpcRequestHandler = async ({ request }) => {
+  const { chainId = '0x1' } = (request.params as BaseParams) ?? {};
+  await switchChain(chainId);
+
   switch (request.method) {
     case 'getGasPrice':
       return await getGasPrice();

packages/examples/packages/ethereum-provider/src/types.ts

@@ -1,4 +1,10 @@
-export type PersonalSignParams = {
+import type { Hex } from '@metamask/utils';
+
+export type BaseParams = {
+  chainId?: Hex;
+};
+
+export type PersonalSignParams = BaseParams & {
   message: string;
 };
 

packages/snaps-controllers/coverage.json

@@ -1,6 +1,6 @@
 {
-  "branches": 93.64,
+  "branches": 93.67,
   "functions": 98.16,
-  "lines": 98.5,
+  "lines": 98.51,
   "statements": 98.34
 }