feat: add isKeychain function (#3473)

Add type guard function that allows detecting if a given object
conforms to the KeyChain interface.

Author: achingbrain

packages/keychain/src/index.ts

@@ -216,3 +216,18 @@ export function keychain (init: KeychainInit = {}): (components: KeychainCompone
     return new KeychainClass(components, init)
   }
 }
+
+export function isKeychain (obj?: any): obj is Keychain {
+  if (obj == null) {
+    return false
+  }
+
+  return typeof obj.findKeyByName === 'function' &&
+    typeof obj.findKeyById === 'function' &&
+    typeof obj.importKey === 'function' &&
+    typeof obj.exportKey === 'function' &&
+    typeof obj.removeKey === 'function' &&
+    typeof obj.renameKey === 'function' &&
+    typeof obj.listKeys === 'function' &&
+    typeof obj.rotateKeychainPass === 'function'
+}

packages/keychain/test/keychain.spec.ts

@@ -6,6 +6,7 @@ import { expect } from 'aegir/chai'
 import { MemoryDatastore } from 'datastore-core/memory'
 import { Key } from 'interface-datastore/key'
 import { toString as uint8ArrayToString } from 'uint8arrays/to-string'
+import { isKeychain } from '../src/index.js'
 import { Keychain as KeychainClass } from '../src/keychain.js'
 import { importPrivateKey } from '../src/utils/import.js'
 import type { KeychainInit, Keychain, KeyInfo } from '../src/index.js'
@@ -41,6 +42,16 @@ describe('keychain', () => {
     }()).to.eventually.be.ok()
   })
 
+  it('is a keychain', async () => {
+    expect(isKeychain(ks)).to.be.true()
+  })
+
+  it('should not be a keychain', async () => {
+    expect(isKeychain()).to.be.false()
+    expect(isKeychain({})).to.be.false()
+    expect(isKeychain(true)).to.be.false()
+  })
+
   it('can override the self key name', async () => {
     const selfKey = 'other-key'
     const kc = new KeychainClass({

packages/keychain/test/utils/import-export.spec.ts

@@ -1,4 +1,3 @@
-/* eslint-env mocha */
 import { generateKeyPair } from '@libp2p/crypto/keys'
 import { expect } from 'aegir/chai'
 import { base58btc } from 'multiformats/bases/base58'