Re-fix #395 by adjusting the processBeforeResponse option

src/App.spec.ts

@@ -1257,6 +1257,89 @@ describe('App', () => {
  assert.equal(fakeErrorHandler.callCount, dummyReceiverEvents.length);
  });
  });
+
+ describe('processBeforeResponse', () => {
+
+ it('should call ack() after event listener completion', async () => {
+ // Arrange
+ const App = await importApp(overrides); // tslint:disable-line:variable-name
+ const fakeLogger = createFakeLogger();
+ const app = new App({
+ logger: fakeLogger,
+ receiver: fakeReceiver,
+ authorize: sinon.fake.resolves(dummyAuthorizationResult),
+ processBeforeResponse: true,
+ });
+
+ let acknowledged = false;
+
+ app.event('app_home_opened', async ({}) => {
+ await new Promise(resolve => setTimeout(resolve, 200));
+ assert.isFalse(acknowledged);
+ });
+
+ const event = {
+ body: {
+ type: 'event_callback',
+ token: 'XXYYZZ',
+ team_id: 'TXXXXXXXX',
+ api_app_id: 'AXXXXXXXXX',
+ event: {
+ type: 'app_home_opened',
+ event_ts: '1234567890.123456',
+ user: 'UXXXXXXX1',
+ text: 'hello friends!',
+ tab: 'home',
+ view: {},
+ },
+ },
+ respond: noop,
+ ack: async (_res: any) => {
+ acknowledged = true;
+ },
+ };
+
+ // Act
+ await fakeReceiver.sendEvent(event);
+
+ // Assert
+ assert.isTrue(acknowledged);
+ });
+
+ it('should call ack() after command listener completion', async () => {
+ // Arrange
+ const App = await importApp(overrides); // tslint:disable-line:variable-name
+ const fakeLogger = createFakeLogger();
+ const app = new App({
+ logger: fakeLogger,
+ receiver: fakeReceiver,
+ authorize: sinon.fake.resolves(dummyAuthorizationResult),
+ processBeforeResponse: true,
+ });
+
+ let acknowledged = false;
+
+ app.command('/hello', async ({ ack }) => {
+ assert.isFalse(acknowledged);
+ await ack();
+ });
+
+ const event = {
+ ...baseEvent,
+ body: {
+ command: '/hello',
+ },
+ ack: async (_res: any) => {
+ acknowledged = true;
+ },
+ };
+
+ // Act
+ await fakeReceiver.sendEvent(event);
+ // Assert
+ assert.isTrue(acknowledged);
+ });
+ });
  });
  });
 });

src/App.ts

@@ -154,6 +154,9 @@ export default class App {
  /** Receiver - ingests events from the Slack platform */
  private receiver: Receiver;
 
+ /** Always call ack() after event listener completion if true */
+ private processBeforeResponse: boolean = false;
+
  /** Logger */
  private logger: Logger;
 
@@ -256,6 +259,7 @@ export default class App {
  });
  }
  }
+ this.processBeforeResponse = processBeforeResponse;
 
  // Conditionally use a global middleware that ignores events (including messages) that are sent from this app
  if (ignoreSelf) {
@@ -580,8 +584,11 @@ export default class App {
  if (type !== IncomingEventType.Event) {
  listenerArgs.ack = ack;
  } else {
- // Events API requests are acknowledged right away, since there's no data expected
- await ack();
+ // If processBeforeResponse is true, ack() call should be after the listener completion
+ if (!this.processBeforeResponse) {
+ // Events API requests are acknowledged right away, since there's no data expected
+ await ack();
+ }
  }
 
  // Get the client arg
@@ -635,6 +642,9 @@ export default class App {
  } else if (rejectedListenerResults.length > 1) {
  throw new MultipleListenerError(rejectedListenerResults.map(rlr => rlr.reason));
  }
+ if (this.processBeforeResponse && type === IncomingEventType.Event) {
+ await ack();
+ }
  },
  );
  } catch (error) {

src/ExpressReceiver.ts

@@ -96,12 +96,24 @@ export default class ExpressReceiver implements Receiver {
 
  try {
  await this.bolt?.processEvent(event);
- if (storedResponse !== undefined) {
- if (typeof storedResponse === 'string') {
- res.send(storedResponse);
- } else {
- res.json(storedResponse);
+
+ if (this.processBeforeResponse) {
+ let spentMillis = 0;
+ const millisForTimeout = 10;
+ // Wait here until the isAcknowledged is marked as true or 3 seconds have passed
+ while (!isAcknowledged && spentMillis < 3000) {
+ await new Promise(resolve => setTimeout(resolve, millisForTimeout));
+ spentMillis += millisForTimeout;
  }
+ if (isAcknowledged) {
+ this.logger.debug(`The listener execution completed in ${spentMillis} millis`);
+ if (typeof storedResponse === 'string') {
+ res.send(storedResponse);
+ } else {
+ res.json(storedResponse);
+ }
+ this.logger.debug('Acknowledged after the listener completion');
+ } // Otherwise, this Bolt app never responds to this request and above setTimeout outputs an error message
  }
  } catch (err) {
  res.send(500);