Add basic support for account RPC methods in snaps simulator

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

@@ -68,4 +68,21 @@ describe('onRpcRequest', () => {
       await close();
     });
   });
+
+  describe('getAccounts', () => {
+    it('returns the addresses granted access to by the user', async () => {
+      const { request, close } = await installSnap();
+
+      const response = await request({
+        method: 'getAccounts',
+      });
+
+      // Currently, snaps-jest will always return this account.
+      expect(response).toRespondWith([
+        '0xc6d5a3c98ec9073b54fa0969957bd582e8d874bf',
+      ]);
+
+      await close();
+    });
+  });
 });

packages/snaps-simulator/src/features/simulation/middleware.test.ts

@@ -1,11 +1,15 @@
+import { mnemonicPhraseToBytes } from '@metamask/key-tree';
 import { JsonRpcEngine } from 'json-rpc-engine';
 
+import { DEFAULT_SRP } from '../configuration';
 import { createMiscMethodMiddleware } from './middleware';
 
+const hooks = { getMnemonic: async () => mnemonicPhraseToBytes(DEFAULT_SRP) };
+
 describe('createMiscMethodMiddleware', () => {
   it('supports metamask_getProviderState', async () => {
     const engine = new JsonRpcEngine();
-    engine.push(createMiscMethodMiddleware());
+    engine.push(createMiscMethodMiddleware(hooks));
 
     const response = await engine.handle({
       jsonrpc: '2.0',
@@ -25,4 +29,40 @@ describe('createMiscMethodMiddleware', () => {
       },
     });
   });
+
+  it('supports eth_accounts', async () => {
+    const engine = new JsonRpcEngine();
+    engine.push(createMiscMethodMiddleware(hooks));
+
+    const response = await engine.handle({
+      jsonrpc: '2.0',
+      id: 1,
+      method: 'eth_accounts',
+      params: [],
+    });
+
+    expect(response).toStrictEqual({
+      id: 1,
+      jsonrpc: '2.0',
+      result: ['0xc6d5a3c98ec9073b54fa0969957bd582e8d874bf'],
+    });
+  });
+
+  it('supports eth_requestAccounts', async () => {
+    const engine = new JsonRpcEngine();
+    engine.push(createMiscMethodMiddleware(hooks));
+
+    const response = await engine.handle({
+      jsonrpc: '2.0',
+      id: 1,
+      method: 'eth_requestAccounts',
+      params: [],
+    });
+
+    expect(response).toStrictEqual({
+      id: 1,
+      jsonrpc: '2.0',
+      result: ['0xc6d5a3c98ec9073b54fa0969957bd582e8d874bf'],
+    });
+  });
 });

packages/snaps-simulator/src/features/simulation/middleware.ts

@@ -1,3 +1,4 @@
+import { BIP44Node } from '@metamask/key-tree';
 import { logError } from '@metamask/snaps-utils';
 import type {
   JsonRpcEngineEndCallback,
@@ -7,10 +8,50 @@ import type {
   PendingJsonRpcResponse,
 } from 'json-rpc-engine';
 
+/* eslint-disable @typescript-eslint/naming-convention */
 export const methodHandlers = {
-  // eslint-disable-next-line @typescript-eslint/naming-convention
   metamask_getProviderState: getProviderStateHandler,
+  eth_requestAccounts: getAccountsHandler,
+  eth_accounts: getAccountsHandler,
 };
+/* eslint-enable @typescript-eslint/naming-convention */
+
+export type MiscMiddlewareHooks = {
+  getMnemonic: () => Promise<Uint8Array>;
+};
+
+/**
+ * A mock handler for account related methods that always returns the first address for the selected SRP.
+ *
+ * @param _request - Incoming JSON-RPC request, ignored for this specific handler.
+ * @param response - The outgoing JSON-RPC response, modified to return the result.
+ * @param _next - The json-rpc-engine middleware next handler.
+ * @param end - The json-rpc-engine middleware end handler.
+ * @param hooks - Any hooks required by this handler.
+ */
+async function getAccountsHandler(
+  _request: JsonRpcRequest<unknown>,
+  response: PendingJsonRpcResponse<unknown>,
+  _next: JsonRpcEngineNextCallback,
+  end: JsonRpcEngineEndCallback,
+  hooks: MiscMiddlewareHooks,
+) {
+  const { getMnemonic } = hooks;
+
+  const node = await BIP44Node.fromDerivationPath({
+    derivationPath: [
+      await getMnemonic(),
+      `bip32:44'`,
+      `bip32:60'`,
+      `bip32:0'`,
+      `bip32:0`,
+      `bip32:0`,
+    ],
+  });
+
+  response.result = [node.address];
+  return end();
+}
 
 /**
  * A mock handler for metamask_getProviderState that always returns a specific hardcoded result.
@@ -39,12 +80,14 @@ async function getProviderStateHandler(
 /**
  * Creates a middleware for handling misc RPC methods normally handled internally by the MM client.
  *
+ * NOTE: This middleware provides all `hooks` to all handlers and should therefore NOT be used outside of the simulator.
+ *
+ * @param hooks - Any hooks used by the middleware handlers.
  * @returns Nothing.
  */
-export function createMiscMethodMiddleware(): JsonRpcMiddleware<
-  unknown,
-  unknown
-> {
+export function createMiscMethodMiddleware(
+  hooks: MiscMiddlewareHooks,
+): JsonRpcMiddleware<unknown, unknown> {
   // This should probably use createAsyncMiddleware
   // eslint-disable-next-line @typescript-eslint/no-misused-promises
   return async function methodMiddleware(request, response, next, end) {
@@ -53,7 +96,7 @@ export function createMiscMethodMiddleware(): JsonRpcMiddleware<
     if (handler) {
       try {
         // Implementations may or may not be async, so we must await them.
-        return await handler(request, response, next, end);
+        return await handler(request, response, next, end, hooks);
       } catch (error: any) {
         logError(error);
         return end(error);

packages/snaps-simulator/src/features/simulation/sagas.ts

@@ -80,16 +80,20 @@
 
   const srp: string = yield select(getSrp);
 
+  const sharedHooks = {
+    getMnemonic: async () => mnemonicPhraseToBytes(srp),
+  };
+
   const permissionSpecifications = {
     ...buildSnapEndowmentSpecifications(Object.keys(ExcludedSnapEndowments)),
     ...buildSnapRestrictedMethodSpecifications([], {
+      ...sharedHooks,
       // TODO: Add all the hooks required
       encrypt,
       decrypt,
       // TODO: Allow changing this?
       getLocale: async () => Promise.resolve('en'),
       getUnlockPromise: async () => Promise.resolve(true),
-      getMnemonic: async () => mnemonicPhraseToBytes(srp),
       showDialog: async (...args: Parameters<typeof showDialog>) =>
         await runSaga(showDialog, ...args).toPromise(),
       showNativeNotification: async (
@@ -137,7 +141,7 @@
 
   const engine = new JsonRpcEngine();
 
-  engine.push(createMiscMethodMiddleware());
+  engine.push(createMiscMethodMiddleware(sharedHooks));
 
   engine.push(
     permissionController.createPermissionMiddleware({