Add method for setting the hdpath

index.js

@@ -5,6 +5,13 @@ const TrezorConnect = require('trezor-connect').default;
 const { TransactionFactory } = require('@ethereumjs/tx');
 
 const hdPathString = `m/44'/60'/0'/0`;
+const SLIP0044TestnetPath = `m/44'/1'/0'/0`;
+
+const ALLOWED_HD_PATHS = {
+  [hdPathString]: true,
+  [SLIP0044TestnetPath]: true,
+};
+
 const keyringType = 'Trezor Hardware';
 const pathBase = 'm';
 const MAX_INDEX = 1000;
@@ -338,6 +345,35 @@ class TrezorKeyring extends EventEmitter {
     this.paths = {};
   }
 
+  /**
+   * Set the HD path to be used by the keyring. Only known supported HD paths are allowed.
+   *
+   * If the given HD path is already the current HD path, nothing happens. Otherwise the new HD
+   * path is set, and the wallet state is completely reset.
+   *
+   * @throws {Error] Throws if the HD path is not supported.
+   *
+   * @param {string} hdPath - The HD path to set.
+   */
+  setHdPath(hdPath) {
+    if (!ALLOWED_HD_PATHS[hdPath]) {
+      throw new Error(
+        `The setHdPath method does not support setting HD Path to ${hdPath}`,
+      );
+    }
+
+    // Reset HDKey if the path changes
+    if (this.hdPath !== hdPath) {
+      this.hdk = new HDKey();
+      this.accounts = [];
+      this.page = 0;
+      this.perPage = 5;
+      this.unlockedAccount = 0;
+      this.paths = {};
+    }
+    this.hdPath = hdPath;
+  }
+
   /* PRIVATE METHODS */
 
   _normalize(buf) {

test/test-eth-trezor-keyring.js

@@ -476,4 +476,61 @@ describe('TrezorKeyring', function () {
       assert.equal(accounts.length, 0);
     });
   });
+
+  describe('setHdPath', function () {
+    const initialProperties = {
+      hdPath: `m/44'/60'/0'/0`,
+      accounts: ['Account 1'],
+      page: 2,
+      perPage: 10,
+    };
+    const accountToUnlock = 1;
+    const mockPaths = { '0x123': 1 };
+
+    beforeEach(function () {
+      keyring.deserialize(initialProperties);
+      keyring.paths = mockPaths;
+      keyring.setAccountToUnlock(accountToUnlock.toString(16));
+    });
+
+    it('should do nothing if passed an hdPath equal to the current hdPath', async function () {
+      keyring.setHdPath(initialProperties.hdPath);
+      assert.equal(keyring.hdPath, initialProperties.hdPath);
+      assert.deepEqual(keyring.accounts, initialProperties.accounts);
+      assert.equal(keyring.page, initialProperties.page);
+      assert.equal(keyring.perPage, initialProperties.perPage);
+      assert.equal(
+        keyring.hdk._publicKey.toString('hex'),
+        fakeHdKey._publicKey.toString('hex'),
+      );
+      assert.equal(keyring.unlockedAccount, accountToUnlock);
+      assert.deepEqual(keyring.paths, mockPaths);
+    });
+
+    it('should update the hdPath and reset account and page properties if passed a new hdPath', async function () {
+      const SLIP0044TestnetPath = `m/44'/1'/0'/0`;
+
+      keyring.setHdPath(SLIP0044TestnetPath);
+
+      assert.equal(keyring.hdPath, SLIP0044TestnetPath);
+      assert.deepEqual(keyring.accounts, []);
+      assert.equal(keyring.page, 0);
+      assert.equal(keyring.perPage, 5);
+      assert.equal(keyring.hdk._publicKey, null);
+      assert.equal(keyring.unlockedAccount, 0);
+      assert.deepEqual(keyring.paths, {});
+    });
+
+    it('should throw an error if passed an unsupported hdPath', async function () {
+      const unsupportedPath = 'unsupported hdPath';
+      try {
+        keyring.setHdPath(unsupportedPath);
+      } catch (error) {
+        assert.equal(
+          error.message,
+          `The setHdPath method does not support setting HD Path to ${unsupportedPath}`,
+        );
+      }
+    });
+  });
 });