feat: {Btc/Trx}AccountProvider account provider (#6662)

## Explanation

* Adds `{Btc/Trx}AccountProvider` in order to be used for BIP44

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## References

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## Checklist

- [x] I've updated the test suite for new or updated code as appropriate
- [x] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [x] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs),
highlighting breaking changes as necessary
- [ ] I've prepared draft pull requests for clients and consumer
packages to resolve any breaking changes

---------

Co-authored-by: Daniel Rocha <[email protected]>

Author: aganglada

packages/multichain-account-service/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `{Btc/Trx}AccountProvider` account providers ([#6662](https://github.com/MetaMask/core/pull/6662))
+
 ### Changed
 
 - Bump `@metamask/utils` from `^11.8.0` to `^11.8.1` ([#6708](https://github.com/MetaMask/core/pull/6708))

packages/multichain-account-service/src/index.ts

@@ -22,6 +22,10 @@ export {
   EvmAccountProvider,
   SOL_ACCOUNT_PROVIDER_NAME,
   SolAccountProvider,
+  BTC_ACCOUNT_PROVIDER_NAME,
+  BtcAccountProvider,
+  TRX_ACCOUNT_PROVIDER_NAME,
+  TrxAccountProvider,
 } from './providers';
 export { MultichainAccountWallet } from './MultichainAccountWallet';
 export { MultichainAccountGroup } from './MultichainAccountGroup';

packages/multichain-account-service/src/providers/BtcAccountProvider.test.ts

@@ -0,0 +1,342 @@
+import { isBip44Account } from '@metamask/account-api';
+import type { Messenger } from '@metamask/base-controller';
+import type { SnapKeyring } from '@metamask/eth-snap-keyring';
+import { BtcAccountType } from '@metamask/keyring-api';
+import type { KeyringMetadata } from '@metamask/keyring-controller';
+import type {
+  EthKeyring,
+  InternalAccount,
+} from '@metamask/keyring-internal-api';
+
+import { AccountProviderWrapper } from './AccountProviderWrapper';
+import { BtcAccountProvider } from './BtcAccountProvider';
+import {
+  getMultichainAccountServiceMessenger,
+  getRootMessenger,
+  MOCK_BTC_P2TR_ACCOUNT_1,
+  MOCK_BTC_P2WPKH_ACCOUNT_1,
+  MOCK_BTC_P2TR_DISCOVERED_ACCOUNT_1,
+  MOCK_HD_ACCOUNT_1,
+  MOCK_HD_KEYRING_1,
+  MockAccountBuilder,
+} from '../tests';
+import type {
+  AllowedActions,
+  AllowedEvents,
+  MultichainAccountServiceActions,
+  MultichainAccountServiceEvents,
+} from '../types';
+
+class MockBtcKeyring {
+  readonly type = 'MockBtcKeyring';
+
+  readonly metadata: KeyringMetadata = {
+    id: 'mock-btc-keyring-id',
+    name: '',
+  };
+
+  readonly accounts: InternalAccount[];
+
+  constructor(accounts: InternalAccount[]) {
+    this.accounts = accounts;
+  }
+
+  #getIndexFromDerivationPath(derivationPath: string): number {
+    // eslint-disable-next-line prefer-regex-literals
+    const derivationPathIndexRegex = new RegExp(
+      "^m/44'/0'/0'/(?<index>[0-9]+)'$",
+      'u',
+    );
+
+    const matched = derivationPath.match(derivationPathIndexRegex);
+    if (matched?.groups?.index === undefined) {
+      throw new Error('Unable to extract index');
+    }
+
+    const { index } = matched.groups;
+    return Number(index);
+  }
+
+  createAccount: SnapKeyring['createAccount'] = jest
+    .fn()
+    .mockImplementation((_, { derivationPath, index, ...options }) => {
+      // Determine the group index to use - either from derivationPath parsing, explicit index, or fallback
+      let groupIndex: number;
+
+      if (derivationPath !== undefined) {
+        groupIndex = this.#getIndexFromDerivationPath(derivationPath);
+      } else if (index !== undefined) {
+        groupIndex = index;
+      } else {
+        groupIndex = this.accounts.length;
+      }
+
+      // Check if an account already exists for this group index AND account type (idempotent behavior)
+      const found = this.accounts.find(
+        (account) =>
+          isBip44Account(account) &&
+          account.options.entropy.groupIndex === groupIndex &&
+          account.type === options.addressType,
+      );
+
+      if (found) {
+        return found; // Idempotent.
+      }
+
+      // Create new account with the correct group index
+      const baseAccount =
+        options.addressType === BtcAccountType.P2wpkh
+          ? MOCK_BTC_P2WPKH_ACCOUNT_1
+          : MOCK_BTC_P2TR_ACCOUNT_1;
+      const account = MockAccountBuilder.from(baseAccount)
+        .withUuid()
+        .withAddressSuffix(`${this.accounts.length}`)
+        .withGroupIndex(groupIndex)
+        .get();
+      this.accounts.push(account);
+
+      return account;
+    });
+}
+
+/**
+ * Sets up a BtcAccountProvider for testing.
+ *
+ * @param options - Configuration options for setup.
+ * @param options.messenger - An optional messenger instance to use. Defaults to a new Messenger.
+ * @param options.accounts - List of accounts to use.
+ * @returns An object containing the controller instance and the messenger.
+ */
+function setup({
+  messenger = getRootMessenger(),
+  accounts = [],
+}: {
+  messenger?: Messenger<
+    MultichainAccountServiceActions | AllowedActions,
+    MultichainAccountServiceEvents | AllowedEvents
+  >;
+  accounts?: InternalAccount[];
+} = {}): {
+  provider: AccountProviderWrapper;
+  messenger: Messenger<
+    MultichainAccountServiceActions | AllowedActions,
+    MultichainAccountServiceEvents | AllowedEvents
+  >;
+  keyring: MockBtcKeyring;
+  mocks: {
+    handleRequest: jest.Mock;
+    keyring: {
+      createAccount: jest.Mock;
+    };
+  };
+} {
+  const keyring = new MockBtcKeyring(accounts);
+
+  messenger.registerActionHandler(
+    'AccountsController:listMultichainAccounts',
+    () => accounts,
+  );
+
+  const mockHandleRequest = jest
+    .fn()
+    .mockImplementation((address: string) =>
+      keyring.accounts.find((account) => account.address === address),
+    );
+  messenger.registerActionHandler(
+    'SnapController:handleRequest',
+    mockHandleRequest,
+  );
+
+  messenger.registerActionHandler(
+    'KeyringController:withKeyring',
+    async (_, operation) =>
+      operation({
+        // We type-cast here, since `withKeyring` defaults to `EthKeyring` and the
+        // Snap keyring doesn't really implement this interface (this is expected).
+        keyring: keyring as unknown as EthKeyring,
+        metadata: keyring.metadata,
+      }),
+  );
+
+  const multichainMessenger = getMultichainAccountServiceMessenger(messenger);
+  const provider = new AccountProviderWrapper(
+    multichainMessenger,
+    new BtcAccountProvider(multichainMessenger),
+  );
+
+  return {
+    provider,
+    messenger,
+    keyring,
+    mocks: {
+      handleRequest: mockHandleRequest,
+      keyring: {
+        createAccount: keyring.createAccount as jest.Mock,
+      },
+    },
+  };
+}
+
+describe('BtcAccountProvider', () => {
+  it('getName returns Bitcoin', () => {
+    const { provider } = setup({ accounts: [] });
+    expect(provider.getName()).toBe('Bitcoin');
+  });
+
+  it('gets accounts', () => {
+    const accounts = [MOCK_BTC_P2TR_ACCOUNT_1];
+    const { provider } = setup({
+      accounts,
+    });
+
+    expect(provider.getAccounts()).toStrictEqual(accounts);
+  });
+
+  it('gets a specific account', () => {
+    const account = MOCK_BTC_P2TR_ACCOUNT_1;
+    const { provider } = setup({
+      accounts: [account],
+    });
+
+    expect(provider.getAccount(account.id)).toStrictEqual(account);
+  });
+
+  it('throws if account does not exist', () => {
+    const account = MOCK_BTC_P2TR_ACCOUNT_1;
+    const { provider } = setup({
+      accounts: [account],
+    });
+
+    const unknownAccount = MOCK_HD_ACCOUNT_1;
+    expect(() => provider.getAccount(unknownAccount.id)).toThrow(
+      `Unable to find account: ${unknownAccount.id}`,
+    );
+  });
+
+  it('creates accounts', async () => {
+    const accounts = [MOCK_BTC_P2TR_ACCOUNT_1, MOCK_BTC_P2WPKH_ACCOUNT_1];
+    const { provider, keyring } = setup({
+      accounts,
+    });
+
+    const newGroupIndex = accounts.length; // Group-index are 0-based.
+    const newAccounts = await provider.createAccounts({
+      entropySource: MOCK_HD_KEYRING_1.metadata.id,
+      groupIndex: newGroupIndex,
+    });
+    expect(newAccounts).toHaveLength(2);
+    expect(keyring.createAccount).toHaveBeenCalled();
+  });
+
+  it('does not re-create accounts (idempotent)', async () => {
+    const accounts = [MOCK_BTC_P2TR_ACCOUNT_1];
+    const { provider } = setup({
+      accounts,
+    });
+
+    const newAccounts = await provider.createAccounts({
+      entropySource: MOCK_HD_KEYRING_1.metadata.id,
+      groupIndex: 0,
+    });
+    expect(newAccounts).toHaveLength(2);
+    expect(newAccounts[0]).toStrictEqual(MOCK_BTC_P2TR_ACCOUNT_1);
+  });
+
+  it('throws if the account creation process takes too long', async () => {
+    const { provider, mocks } = setup({
+      accounts: [],
+    });
+
+    mocks.keyring.createAccount.mockImplementation(() => {
+      return new Promise((resolve) => {
+        setTimeout(() => {
+          resolve(MOCK_BTC_P2TR_ACCOUNT_1);
+        }, 4000);
+      });
+    });
+
+    await expect(
+      provider.createAccounts({
+        entropySource: MOCK_HD_KEYRING_1.metadata.id,
+        groupIndex: 0,
+      }),
+    ).rejects.toThrow('Timed out');
+  });
+
+  // Skip this test for now, since we manually inject those options upon
+  // account creation, so it cannot fails (until the Bitcoin Snap starts
+  // using the new typed options).
+  // eslint-disable-next-line jest/no-disabled-tests
+  it.skip('throws if the created account is not BIP-44 compatible', async () => {
+    const accounts = [MOCK_BTC_P2TR_ACCOUNT_1];
+    const { provider, mocks } = setup({
+      accounts,
+    });
+
+    mocks.keyring.createAccount.mockResolvedValue({
+      ...MOCK_BTC_P2TR_ACCOUNT_1,
+      options: {}, // No options, so it cannot be BIP-44 compatible.
+    });
+
+    await expect(
+      provider.createAccounts({
+        entropySource: MOCK_HD_KEYRING_1.metadata.id,
+        groupIndex: 0,
+      }),
+    ).rejects.toThrow('Created account is not BIP-44 compatible');
+  });
+
+  it('discover accounts at a new group index creates an account', async () => {
+    const { provider, mocks } = setup({
+      accounts: [],
+    });
+
+    // Simulate one discovered account at the requested index.
+    mocks.handleRequest.mockReturnValue([MOCK_BTC_P2TR_DISCOVERED_ACCOUNT_1]);
+
+    const discovered = await provider.discoverAccounts({
+      entropySource: MOCK_HD_KEYRING_1.metadata.id,
+      groupIndex: 0,
+    });
+
+    expect(discovered).toHaveLength(2);
+    // Ensure we did go through creation path
+    expect(mocks.keyring.createAccount).toHaveBeenCalled();
+    // Provider should now expose one account (newly created)
+    expect(provider.getAccounts()).toHaveLength(2);
+  });
+
+  it('returns existing account if it already exists at index', async () => {
+    const { provider, mocks } = setup({
+      accounts: [MOCK_BTC_P2TR_ACCOUNT_1, MOCK_BTC_P2WPKH_ACCOUNT_1],
+    });
+
+    // Simulate one discovered account — should resolve to the existing one
+    mocks.handleRequest.mockReturnValue([MOCK_BTC_P2TR_DISCOVERED_ACCOUNT_1]);
+
+    const discovered = await provider.discoverAccounts({
+      entropySource: MOCK_HD_KEYRING_1.metadata.id,
+      groupIndex: 0,
+    });
+
+    expect(discovered).toStrictEqual([
+      MOCK_BTC_P2TR_ACCOUNT_1,
+      MOCK_BTC_P2WPKH_ACCOUNT_1,
+    ]);
+  });
+
+  it('does not return any accounts if no account is discovered', async () => {
+    const { provider, mocks } = setup({
+      accounts: [],
+    });
+
+    mocks.handleRequest.mockReturnValue([]);
+
+    const discovered = await provider.discoverAccounts({
+      entropySource: MOCK_HD_KEYRING_1.metadata.id,
+      groupIndex: 0,
+    });
+
+    expect(discovered).toStrictEqual([]);
+  });
+});