fix: allow passing gax instance to client constructor (#249)

- [ ] Regenerate this pull request now.

PiperOrigin-RevId: 470911839

Source-Link: googleapis/googleapis@3527566

Source-Link: googleapis/googleapis-gen@f16a1d2
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiZjE2YTFkMjI0ZjAwYTYzMGVhNDNkNmE5YTFhMzFmNTY2ZjQ1Y2RlYSJ9

feat: accept google-gax instance as a parameter
Please see the documentation of the client constructor for details.

PiperOrigin-RevId: 470332808

Source-Link: googleapis/googleapis@d4a2367

Source-Link: googleapis/googleapis-gen@e97a1ac
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiZTk3YTFhYzIwNGVhZDRmZTczNDFmOTFlNzJkYjdjNmFjNjAxNjM0MSJ9

packages/google-cloud-mediatranslation/src/v1beta1/speech_translation_service_client.ts

@@ -17,15 +17,13 @@
 // ** All changes to this file may be overwritten. **
 
 /* global window */
-import * as gax from 'google-gax';
-import {
+import type * as gax from 'google-gax';
+import type {
   Callback,
   CallOptions,
   Descriptors,
   ClientOptions,
-  GoogleError,
 } from 'google-gax';
-
 import {PassThrough} from 'stream';
 import * as protos from '../../protos/protos';
 import jsonProtos = require('../../protos/protos.json');
@@ -35,7 +33,6 @@ import jsonProtos = require('../../protos/protos.json');
  * This file defines retry strategy and timeouts for all API methods in this library.
  */
 import * as gapicConfig from './speech_translation_service_client_config.json';
-
 const version = require('../../../package.json').version;
 
 /**
@@ -94,8 +91,18 @@ export class SpeechTranslationServiceClient {
    *     Pass "rest" to use HTTP/1.1 REST API instead of gRPC.
    *     For more information, please check the
    *     {@link https://github.com/googleapis/gax-nodejs/blob/main/client-libraries.md#http11-rest-api-mode documentation}.
+   * @param {gax} [gaxInstance]: loaded instance of `google-gax`. Useful if you
+   *     need to avoid loading the default gRPC version and want to use the fallback
+   *     HTTP implementation. Load only fallback version and pass it to the constructor:
+   *     ```
+   *     const gax = require('google-gax/build/src/fallback'); // avoids loading google-gax with gRPC
+   *     const client = new SpeechTranslationServiceClient({fallback: 'rest'}, gax);
+   *     ```
    */
-  constructor(opts?: ClientOptions) {
+  constructor(
+    opts?: ClientOptions,
+    gaxInstance?: typeof gax | typeof gax.fallback
+  ) {
     // Ensure that options include all the required fields.
     const staticMembers = this
       .constructor as typeof SpeechTranslationServiceClient;
@@ -116,8 +123,13 @@ export class SpeechTranslationServiceClient {
       opts['scopes'] = staticMembers.scopes;
     }
 
+    // Load google-gax module synchronously if needed
+    if (!gaxInstance) {
+      gaxInstance = require('google-gax') as typeof gax;
+    }
+
     // Choose either gRPC or proto-over-HTTP implementation of google-gax.
-    this._gaxModule = opts.fallback ? gax.fallback : gax;
+    this._gaxModule = opts.fallback ? gaxInstance.fallback : gaxInstance;
 
     // Create a `gaxGrpc` object, with any grpc-specific options sent to the client.
     this._gaxGrpc = new this._gaxModule.GrpcClient(opts);
@@ -161,7 +173,7 @@ export class SpeechTranslationServiceClient {
     // Provide descriptors for these.
     this.descriptors.stream = {
       streamingTranslateSpeech: new this._gaxModule.StreamDescriptor(
-        gax.StreamType.BIDI_STREAMING,
+        this._gaxModule.StreamType.BIDI_STREAMING,
         opts.fallback === 'rest'
       ),
     };
@@ -180,7 +192,7 @@ export class SpeechTranslationServiceClient {
     this.innerApiCalls = {};
 
     // Add a warn function to the client constructor so it can be easily tested.
-    this.warn = gax.warn;
+    this.warn = this._gaxModule.warn;
   }
 
   /**
@@ -227,7 +239,9 @@ export class SpeechTranslationServiceClient {
                 setImmediate(() => {
                   stream.emit(
                     'error',
-                    new GoogleError('The client has already been closed.')
+                    new this._gaxModule.GoogleError(
+                      'The client has already been closed.'
+                    )
                   );
                 });
                 return stream;