fix: update masks for topic should be snake case

package.json

@@ -61,7 +61,6 @@
     "google-gax": "^3.6.1",
     "heap-js": "^2.2.0",
     "is-stream-ended": "^0.1.4",
-    "lodash.snakecase": "^4.1.1",
     "p-defer": "^3.0.0"
   },
   "devDependencies": {

src/subscription.ts

@@ -17,7 +17,6 @@
 import {EventEmitter} from 'events';
 import * as extend from 'extend';
 import {CallOptions} from 'google-gax';
-import snakeCase = require('lodash.snakecase');
 
 import {google} from '../protos/protos';
 
@@ -44,7 +43,7 @@ import {
 } from './snapshot';
 import {Subscriber, SubscriberOptions} from './subscriber';
 import {Topic} from './topic';
-import {promisifySome} from './util';
+import {camelToSnake, promisifySome} from './util';
 
 export {AckError, AckResponse, AckResponses} from './subscriber';
 
@@ -1100,7 +1099,7 @@ export class Subscription extends EventEmitter {
     callback = typeof optsOrCallback === 'function' ? optsOrCallback : callback;
 
     const subscription = Subscription.formatMetadata_(metadata);
-    const fields = Object.keys(subscription).map(snakeCase);
+    const fields = Object.keys(subscription).map(camelToSnake);
     subscription.name = this.name;
     const reqOpts = {
       subscription,

src/topic.ts

@@ -47,7 +47,7 @@ import {
   Subscription,
   SubscriptionOptions,
 } from './subscription';
-import {promisifySome} from './util';
+import {camelToSnake, promisifySome} from './util';
 
 export type TopicMetadata = google.pubsub.v1.ITopic;
 
@@ -951,7 +951,7 @@ export class Topic {
     callback = typeof optsOrCallback === 'function' ? optsOrCallback : callback;
 
     const topic = Object.assign({name: this.name}, options);
-    const updateMask = {paths: Object.keys(options)};
+    const updateMask = {paths: Object.keys(options).map(camelToSnake)};
     const reqOpts = {topic, updateMask};
 
     this.request<TopicMetadata>(

src/util.ts

@@ -83,3 +83,12 @@ export function addToBucket<T, U>(map: Map<T, U[]>, bucket: T, item: U) {
   items.push(item);
   map.set(bucket, items);
 }
+
+/**
+ * Converts a string from camelCase to snake_case.
+ *
+ * @private
+ */
+export function camelToSnake(input: string): string {
+  return input.replace(/[A-Z]/g, letter => `_${letter.toLowerCase()}`);
+}