fix: update masks for topic should be snake case

src/topic.ts

@@ -48,6 +48,7 @@ import {
   SubscriptionOptions,
 } from './subscription';
 import {promisifySome} from './util';
+import snakeCase = require('lodash.snakecase');
 
 export type TopicMetadata = google.pubsub.v1.ITopic;
 
@@ -951,7 +952,7 @@ 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(snakeCase)};
     const reqOpts = {topic, updateMask};
 
     this.request<TopicMetadata>(

system-test/pubsub.ts

@@ -307,6 +307,22 @@ describe('pubsub', () => {
       );
     });
 
+    it('should set metadata for a topic', async () => {
+      const threeDaysInSeconds = 3 * 24 * 60 * 60;
+
+      const topic = pubsub.topic(TOPIC_NAMES[0]);
+      await topic.setMetadata({
+        messageRetentionDuration: {
+          seconds: threeDaysInSeconds,
+        },
+      });
+      const [metadata] = await topic.getMetadata();
+      const {seconds, nanos} = metadata.messageRetentionDuration!;
+
+      assert.strictEqual(Number(seconds), threeDaysInSeconds);
+      assert.strictEqual(Number(nanos), 0);
+    });
+
     describe('ordered messages', () => {
       interface Expected {
         key: string;

test/topic.ts

@@ -671,6 +671,7 @@ describe('Topic', () => {
   describe('setMetadata', () => {
     const METADATA = {
       labels: {yee: 'haw'},
+      messageRetentionDuration: {moo: 'cows'},
     };
 
     let requestStub: sinon.SinonStub;
@@ -691,7 +692,9 @@ describe('Topic', () => {
       topic.setMetadata(METADATA, assert.ifError);
 
       const expectedTopic = Object.assign({name: topic.name}, METADATA);
-      const expectedUpdateMask = {paths: ['labels']};
+      const expectedUpdateMask = {
+        paths: ['labels', 'message_retention_duration'],
+      };
 
       const [{reqOpts}] = requestStub.lastCall.args;
       assert.deepStrictEqual(reqOpts.topic, expectedTopic);