feat: PassThrough AuthClient (#1771)

* feat: `PassThrough` AuthClient

* refactor: Expand Types

src/auth/authclient.ts

@@ -17,7 +17,7 @@ import {Gaxios, GaxiosOptions, GaxiosPromise, GaxiosResponse} from 'gaxios';
 
 import {DefaultTransporter, Transporter} from '../transporters';
 import {Credentials} from './credentials';
-import {Headers} from './oauth2client';
+import {GetAccessTokenResponse, Headers} from './oauth2client';
 import {OriginalAndCamel, originalOrCamelOptions} from '../util';
 
 /**
@@ -128,10 +128,7 @@ export interface CredentialsClient {
    * @return A promise that resolves with the current GCP access token
    *   response. If the current credential is expired, a new one is retrieved.
    */
-  getAccessToken(): Promise<{
-    token?: string | null;
-    res?: GaxiosResponse | null;
-  }>;
+  getAccessToken(): Promise<GetAccessTokenResponse>;
 
   /**
    * The main authentication interface. It takes an optional url which when

src/auth/passthrough.ts

@@ -0,0 +1,65 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import {GaxiosOptions} from 'gaxios';
+import {AuthClient} from './authclient';
+import {GetAccessTokenResponse, Headers} from './oauth2client';
+
+/**
+ * An AuthClient without any Authentication information. Useful for:
+ * - Anonymous access
+ * - Local Emulators
+ * - Testing Environments
+ *
+ */
+export class PassThroughClient extends AuthClient {
+  /**
+   * Creates a request without any authentication headers or checks.
+   *
+   * @remarks
+   *
+   * In testing environments it may be useful to change the provided
+   * {@link AuthClient.transporter} for any desired request overrides/handling.
+   *
+   * @param opts
+   * @returns The response of the request.
+   */
+  async request<T>(opts: GaxiosOptions) {
+    return this.transporter.request<T>(opts);
+  }
+
+  /**
+   * A required method of the base class.
+   * Always will return an empty object.
+   *
+   * @returns {}
+   */
+  async getAccessToken(): Promise<GetAccessTokenResponse> {
+    return {};
+  }
+
+  /**
+   * A required method of the base class.
+   * Always will return an empty object.
+   *
+   * @returns {}
+   */
+  async getRequestHeaders(): Promise<Headers> {
+    return {};
+  }
+}
+
+const a = new PassThroughClient();
+
+a.getAccessToken();

src/index.ts

@@ -68,6 +68,7 @@ export {
   PluggableAuthClient,
   PluggableAuthClientOptions,
 } from './auth/pluggable-auth-client';
+export {PassThroughClient} from './auth/passthrough';
 export {DefaultTransporter} from './transporters';
 
 const auth = new GoogleAuth();

test/test.authclient.ts

@@ -14,29 +14,10 @@
 
 import {strict as assert} from 'assert';
 
-import {GaxiosOptions, GaxiosPromise, GaxiosResponse} from 'gaxios';
-import {AuthClient} from '../src';
-import {Headers} from '../src/auth/oauth2client';
+import {PassThroughClient} from '../src';
 import {snakeToCamel} from '../src/util';
 
 describe('AuthClient', () => {
-  class TestAuthClient extends AuthClient {
-    request<T>(opts: GaxiosOptions): GaxiosPromise<T> {
-      throw new Error('Method not implemented.');
-    }
-
-    getRequestHeaders(url?: string | undefined): Promise<Headers> {
-      throw new Error('Method not implemented.');
-    }
-
-    getAccessToken(): Promise<{
-      token?: string | null | undefined;
-      res?: GaxiosResponse<any> | null | undefined;
-    }> {
-      throw new Error('Method not implemented.');
-    }
-  }
-
   it('should accept and normalize snake case options to camel case', () => {
     const expected = {
       project_id: 'my-projectId',
@@ -49,11 +30,11 @@ describe('AuthClient', () => {
       const camelCased = snakeToCamel(key) as keyof typeof authClient;
 
       // assert snake cased input
-      let authClient = new TestAuthClient({[key]: value});
+      let authClient = new PassThroughClient({[key]: value});
       assert.equal(authClient[camelCased], value);
 
       // assert camel cased input
-      authClient = new TestAuthClient({[camelCased]: value});
+      authClient = new PassThroughClient({[camelCased]: value});
       assert.equal(authClient[camelCased], value);
     }
   });

test/test.passthroughclient.ts

@@ -0,0 +1,62 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import {strict as assert} from 'assert';
+
+import * as nock from 'nock';
+
+import {PassThroughClient} from '../src';
+
+describe('AuthClient', () => {
+  before(async () => {
+    nock.disableNetConnect();
+  });
+
+  afterEach(async () => {
+    nock.cleanAll();
+  });
+
+  describe('#getAccessToken', () => {
+    it('should return an empty object', async () => {
+      const client = new PassThroughClient();
+      const token = await client.getAccessToken();
+
+      assert.deepEqual(token, {});
+    });
+  });
+
+  describe('#getRequestHeaders', () => {
+    it('should return an empty object', async () => {
+      const client = new PassThroughClient();
+      const token = await client.getRequestHeaders();
+
+      assert.deepEqual(token, {});
+    });
+  });
+
+  describe('#request', () => {
+    it('should return the expected response', async () => {
+      const url = 'https://google.com';
+      const example = {test: 'payload'};
+      const scope = nock(url).get('/').reply(200, example);
+
+      const client = new PassThroughClient();
+      const response = await client.request({url});
+
+      assert.deepEqual(response.data, example);
+
+      scope.done();
+    });
+  });
+});