feat(account-api): add isBip44Account helper (#319)

Add `isBip44Account` which can be used to detect if an `Account` type
(`KeyringAcccount` compatible) is compatible with BIP-44 (according to
the new typed options).

Author: ccharly

packages/account-api/package.json

@@ -47,7 +47,8 @@
   },
   "dependencies": {
     "@metamask/keyring-api": "workspace:^",
-    "@metamask/keyring-utils": "workspace:^"
+    "@metamask/keyring-utils": "workspace:^",
+    "@metamask/superstruct": "^3.1.0"
   },
   "devDependencies": {
     "@lavamoat/allow-scripts": "^3.2.1",

packages/account-api/src/api/bip44.ts

@@ -0,0 +1,33 @@
+import type {
+  KeyringAccount,
+  KeyringAccountEntropyMnemonicOptions,
+} from '@metamask/keyring-api';
+import { KeyringAccountEntropyMnemonicOptionsStruct } from '@metamask/keyring-api';
+import { is } from '@metamask/superstruct';
+
+/**
+ * BIP-44 compatible account type.
+ */
+export type Bip44Account<Account extends KeyringAccount> = Account & {
+  // We force the option type for those accounts. (That's how we identify
+  // if an account is BIP-44 compatible).
+  options: {
+    entropy: KeyringAccountEntropyMnemonicOptions;
+  };
+};
+
+/**
+ * Checks if an account is BIP-44 compatible.
+ *
+ * @param account - The account to be tested.
+ * @returns True if the account is BIP-44 compatible.
+ */
+export function isBip44Account<Account extends KeyringAccount>(
+  account: Account,
+): account is Bip44Account<Account> {
+  // To be BIP-44 compatible, you just need to use this set of options:
+  return is(
+    account.options.entropy,
+    KeyringAccountEntropyMnemonicOptionsStruct,
+  );
+}

packages/account-api/src/api/index.ts

@@ -1,3 +1,4 @@
+export * from './bip44';
 export * from './group';
 export * from './wallet';
 export type * from './provider';

packages/account-api/src/index.test.ts

@@ -2,6 +2,7 @@
 
 import type {
   EntropySourceId,
+  KeyringAccountEntropyMnemonicOptions,
   KeyringAccountOptions,
 } from '@metamask/keyring-api';
 import {
@@ -37,6 +38,7 @@ import {
   MultichainAccount,
   MultichainAccountWallet,
   getGroupIndexFromMultichainAccountId,
+  isBip44Account,
 } from './api';
 
 const mockEntropySource = 'mock-entropy-source';
@@ -651,4 +653,73 @@ describe('index', () => {
       ).toThrow('Unable to extract group index');
     });
   });
+
+  describe('bip44', () => {
+    describe('isBip44Account', () => {
+      it('returns true if the account is BIP-44 compatible', () => {
+        expect(isBip44Account(mockEvmAccount)).toBe(true);
+      });
+
+      it.each([
+        {
+          tc: 'missing type',
+          options: {
+            entropy: {
+              // Missing type.
+              id: mockEntropySource,
+              groupIndex: 0,
+              derivationPath: '',
+            },
+          },
+        },
+        {
+          tc: 'missing id',
+          options: {
+            entropy: {
+              type: KeyringAccountEntropyTypeOption.Mnemonic,
+              // Missing id.
+              groupIndex: 0,
+              derivationPath: '',
+            },
+          },
+        },
+        {
+          tc: 'missing groupIndex',
+          options: {
+            entropy: {
+              type: 'mnemonic',
+              id: mockEntropySource,
+              // Missing groupIndex.
+              derivationPath: '',
+            },
+          },
+        },
+        {
+          tc: 'missing derivationPath',
+          options: {
+            entropy: {
+              type: 'mnemonic',
+              id: mockEntropySource,
+              groupIndex: 0,
+              // Missing derivationPath.
+            },
+          },
+        },
+      ])(
+        'returns false if the account is not BIP-44 compatible with: $tc',
+        ({ options }) => {
+          const account = {
+            ...mockEvmAccount,
+            options: {
+              entropy:
+                // Force the error case here.
+                options as unknown as KeyringAccountEntropyMnemonicOptions,
+            },
+          };
+
+          expect(isBip44Account(account)).toBe(false);
+        },
+      );
+    });
+  });
 });

yarn.lock

@@ -1365,6 +1365,7 @@ __metadata:
     "@metamask/keyring-api": "workspace:^"
     "@metamask/keyring-internal-api": "workspace:^"
     "@metamask/keyring-utils": "workspace:^"
+    "@metamask/superstruct": "npm:^3.1.0"
     "@ts-bridge/cli": "npm:^0.6.3"
     "@types/jest": "npm:^29.5.12"
     "@types/node": "npm:^20.12.12"