feat: Support AuthClient for authClient

package.json

@@ -38,7 +38,7 @@
     "duplexify": "^4.1.1",
     "ent": "^2.2.0",
     "extend": "^3.0.2",
-    "google-auth-library": "^7.9.2",
+    "google-auth-library": "^7.14.0",
     "retry-request": "^4.2.2",
     "teeny-request": "^7.0.0"
   },

src/service.ts

@@ -18,7 +18,7 @@
 
 import arrify = require('arrify');
 import * as extend from 'extend';
-import {GoogleAuth, GoogleAuthOptions} from 'google-auth-library';
+import {AuthClient, GoogleAuth, GoogleAuthOptions} from 'google-auth-library';
 import * as r from 'teeny-request';
 
 import {Interceptor} from './service-object';
@@ -57,13 +57,13 @@ export interface ServiceConfig {
   packageJson: PackageJson;
 
   /**
-   * Reuse an existing GoogleAuth client instead of creating a new one.
+   * Reuse an existing `AuthClient` or `GoogleAuth` client instead of creating a new one.
    */
-  authClient?: GoogleAuth;
+  authClient?: AuthClient | GoogleAuth;
 }
 
-export interface ServiceOptions extends GoogleAuthOptions {
-  authClient?: GoogleAuth;
+export interface ServiceOptions extends Omit<GoogleAuthOptions, 'authClient'> {
+  authClient?: AuthClient | GoogleAuth;
   interceptors_?: Interceptor[];
   email?: string;
   token?: string;
@@ -81,7 +81,7 @@ export class Service {
   private projectIdRequired: boolean;
   providedUserAgent?: string;
   makeAuthenticatedRequest: MakeAuthenticatedRequest;
-  authClient: GoogleAuth;
+  authClient: GoogleAuth<AuthClient>;
   private getCredentials: {};
   readonly apiEndpoint: string;
   timeout?: number;

src/util.ts

@@ -19,7 +19,7 @@
 import {replaceProjectIdToken} from '@google-cloud/projectify';
 import * as ent from 'ent';
 import * as extend from 'extend';
-import {GoogleAuth, GoogleAuthOptions} from 'google-auth-library';
+import {AuthClient, GoogleAuth, GoogleAuthOptions} from 'google-auth-library';
 import {CredentialBody} from 'google-auth-library';
 import * as r from 'teeny-request';
 import * as retryRequest from 'retry-request';
@@ -111,7 +111,7 @@ export interface MakeAuthenticatedRequest {
   getCredentials: (
     callback: (err?: Error | null, credentials?: CredentialBody) => void
   ) => void;
-  authClient: GoogleAuth;
+  authClient: GoogleAuth<AuthClient>;
 }
 
 export interface Abortable {
@@ -125,7 +125,7 @@ export interface PackageJson {
 }
 
 export interface MakeAuthenticatedRequestFactoryConfig
-  extends GoogleAuthOptions {
+  extends Omit<GoogleAuthOptions, 'authClient'> {
   /**
    * Automatically retry requests if the response is related to rate limits or
    * certain intermittent server errors. We will exponentially backoff
@@ -157,10 +157,10 @@ export interface MakeAuthenticatedRequestFactoryConfig
   stream?: Duplexify;
 
   /**
-   * A pre-instantiated GoogleAuth client that should be used.
+   * A pre-instantiated `AuthClient` or `GoogleAuth` client that should be used.
    * A new will be created if this is not set.
    */
-  authClient?: GoogleAuth;
+  authClient?: AuthClient | GoogleAuth;
 }
 
 export interface MakeAuthenticatedRequestOptions {
@@ -591,8 +591,21 @@ export class Util {
     if (googleAutoAuthConfig.projectId === '{{projectId}}') {
       delete googleAutoAuthConfig.projectId;
     }
-    const authClient =
-      googleAutoAuthConfig.authClient || new GoogleAuth(googleAutoAuthConfig);
+
+    let authClient: GoogleAuth<AuthClient>;
+
+    if (googleAutoAuthConfig.authClient instanceof GoogleAuth) {
+      // Use an existing `GoogleAuth`
+      authClient = googleAutoAuthConfig.authClient;
+    } else {
+      // Pass an `AuthClient` to `GoogleAuth`, if available
+      const config = {
+        ...googleAutoAuthConfig,
+        authClient: googleAutoAuthConfig.authClient,
+      };
+
+      authClient = new GoogleAuth(config);
+    }
 
     /**
      * The returned function that will make an authenticated request.
@@ -659,7 +672,7 @@ export class Util {
             // A projectId was required, but we don't have one.
             // Re-use the "Could not load the default credentials error" if
             // auto auth failed.
-            err = err || e;
+            err = err || (e as Error);
           }
         }
 

test/service-object.ts

@@ -23,6 +23,7 @@ import * as extend from 'extend';
 import * as proxyquire from 'proxyquire';
 import * as r from 'teeny-request';
 import * as sinon from 'sinon';
+import {AuthClient, OAuth2Client} from 'google-auth-library';
 
 import {Service} from '../src';
 import * as SO from '../src/service-object';

test/service.ts

@@ -17,6 +17,7 @@ import {describe, it, before, beforeEach, after} from 'mocha';
 import * as extend from 'extend';
 import * as proxyquire from 'proxyquire';
 import {Request} from 'teeny-request';
+import {AuthClient, GoogleAuth, OAuth2Client} from 'google-auth-library';
 
 import {Interceptor} from '../src';
 import {ServiceConfig, ServiceOptions} from '../src/service';
@@ -69,7 +70,7 @@ describe('Service', () => {
   };
 
   const OPTIONS = {
-    authClient: {getCredentials: () => {}},
+    authClient: new GoogleAuth(),
     credentials: {},
     keyFile: {},
     email: 'email',
@@ -130,11 +131,39 @@ describe('Service', () => {
       assert.strictEqual(service.authClient, OPTIONS.authClient);
     });
 
-    it('should allow passing a custom GoogleAuth client', () => {
-      const authClient = {getCredentials: () => {}};
-      const cfg = Object.assign({}, {authClient}, CONFIG);
-      const service = new Service(cfg);
-      assert.strictEqual(service.authClient, authClient);
+    describe('`AuthClient` support', () => {
+      // Using a custom `AuthClient` to ensure any `AuthClient` would work
+      class CustomAuthClient extends AuthClient {
+        async getAccessToken() {
+          return {token: '', res: undefined};
+        }
+
+        async getRequestHeaders() {
+          return {};
+        }
+
+        request = OAuth2Client.prototype.request.bind(this);
+      }
+
+      it('should accept an `AuthClient` passed to config', async () => {
+        const authClient = new CustomAuthClient();
+        const serviceObject = new Service({...CONFIG, authClient});
+
+        // The custom `AuthClient` should be passed to `GoogleAuth` and used internally
+        const client = await serviceObject.authClient.getClient();
+
+        assert.strictEqual(client, authClient);
+      });
+
+      it('should accept an `AuthClient` passed to options', async () => {
+        const authClient = new CustomAuthClient();
+        const serviceObject = new Service(CONFIG, {authClient});
+
+        // The custom `AuthClient` should be passed to `GoogleAuth` and used internally
+        const client = await serviceObject.authClient.getClient();
+
+        assert.strictEqual(client, authClient);
+      });
     });
 
     it('should localize the baseUrl', () => {

test/util.ts

@@ -16,7 +16,12 @@ import {replaceProjectIdToken} from '@google-cloud/projectify';
 import * as assert from 'assert';
 import {describe, it, before, beforeEach, afterEach} from 'mocha';
 import * as extend from 'extend';
-import {GoogleAuth, GoogleAuthOptions} from 'google-auth-library';
+import {
+  AuthClient,
+  GoogleAuth,
+  GoogleAuthOptions,
+  OAuth2Client,
+} from 'google-auth-library';
 import * as nock from 'nock';
 import * as proxyquire from 'proxyquire';
 import * as r from 'teeny-request';
@@ -113,6 +118,18 @@ describe('common/util', () => {
   }
 
   const fakeGoogleAuth = {
+    // Using a custom `AuthClient` to ensure any `AuthClient` would work
+    AuthClient: class CustomAuthClient extends AuthClient {
+      async getAccessToken() {
+        return {token: '', res: undefined};
+      }
+
+      async getRequestHeaders() {
+        return {};
+      }
+
+      request = OAuth2Client.prototype.request.bind(this);
+    },
     GoogleAuth: class {
       constructor(config?: GoogleAuthOptions) {
         return new GoogleAuth(config);
@@ -590,7 +607,7 @@ describe('common/util', () => {
       const fakeStream = new stream.Writable();
       const error = new Error('Error.');
       fakeStream.write = () => false;
-      dup.end = () => {};
+      dup.end = () => dup;
 
       stub('handleResp', (err, res, body, callback) => {
         callback(error);
@@ -705,6 +722,24 @@ describe('common/util', () => {
     it('should create an authClient', done => {
       const config = {test: true} as MakeAuthenticatedRequestFactoryConfig;
 
+      sandbox
+        .stub(fakeGoogleAuth, 'GoogleAuth')
+        .callsFake((config_: GoogleAuthOptions) => {
+          assert.deepStrictEqual(config_, {...config, authClient: undefined});
+          setImmediate(done);
+          return authClient;
+        });
+
+      util.makeAuthenticatedRequestFactory(config);
+    });
+
+    it('should pass an `AuthClient` to `GoogleAuth` when provided', done => {
+      const customAuthClient = new fakeGoogleAuth.AuthClient();
+
+      const config: MakeAuthenticatedRequestFactoryConfig = {
+        authClient: customAuthClient,
+      };
+
       sandbox
         .stub(fakeGoogleAuth, 'GoogleAuth')
         .callsFake((config_: GoogleAuthOptions) => {