Fix #757 Add event type name validation & channel_type filter middleware

src/App.spec.ts

@@ -560,6 +560,13 @@ describe('App', () => {
         assert(error.code === ErrorCode.MultipleListenerError);
         assert.sameMembers(error.originals, errorsToThrow);
       });
+
+      it('should detect invalid event names', async () => {
+        app.event('app_mention', async () => {});
+        app.event('message', async () => {});
+        assert.throws(() => app.event('message.channels', async () => {}), 'Although the document mentions');
+        assert.throws(() => app.event(/message\..+/, async () => {}), 'Although the document mentions');
+      });
     });
 
     describe('WorkflowStep middleware', () => {

src/App.ts

@@ -422,6 +422,21 @@ export default class App {
     eventNameOrPattern: EventType,
     ...listeners: Middleware<SlackEventMiddlewareArgs<string>>[]
   ): void {
+    let invalidEventName = false;
+    if (typeof eventNameOrPattern === 'string') {
+      const name = eventNameOrPattern as string;
+      invalidEventName = name.startsWith('message.');
+    } else if (eventNameOrPattern instanceof RegExp) {
+      const name = (eventNameOrPattern as RegExp).source;
+      invalidEventName = name.startsWith('message\\.');
+    }
+    if (invalidEventName) {
+      throw new AppInitializationError(
+        `Although the document mentions "${eventNameOrPattern}",` +
+          'it is not a valid event type. Use "message" instead. ' +
+          'If you want to filter message events, you can use event.channel_type for it.',
+      );
+    }
     this.listeners.push([
       onlyEvents,
       matchEventType(eventNameOrPattern),