Merge pull request #908 from pooreumu/fix-error-handling

fix(): catch unhandled exceptions

lib/decorators/on-event.decorator.ts

@@ -33,9 +33,9 @@ export const OnEvent = (
 ): MethodDecorator => {
   const decoratorFactory = (target: object, key?: any, descriptor?: any) => {
     extendArrayMetadata(
-        EVENT_LISTENER_METADATA,
-        [{ event, options } as OnEventMetadata],
-        descriptor.value,
+      EVENT_LISTENER_METADATA,
+      [{ event, options } as OnEventMetadata],
+      descriptor.value,
     );
     return descriptor;
   };

lib/event-subscribers.loader.ts

@@ -1,5 +1,6 @@
 import {
   Injectable,
+  Logger,
   OnApplicationBootstrap,
   OnApplicationShutdown,
 } from '@nestjs/common';
@@ -24,6 +25,7 @@ export class EventSubscribersLoader
   implements OnApplicationBootstrap, OnApplicationShutdown
 {
   private readonly injector = new Injector();
+  private readonly logger = new Logger('Event');
 
   constructor(
     private readonly discoveryService: DiscoveryService,
@@ -92,7 +94,8 @@ export class EventSubscribersLoader
       } else {
         listenerMethod(
           event,
-          (...args: unknown[]) => instance[methodKey].call(instance, ...args),
+          (...args: unknown[]) =>
+            this.wrapFunctionInTryCatchBlocks(instance, methodKey, args),
           options,
         );
       }
@@ -135,9 +138,10 @@ export class EventSubscribersLoader
           moduleRef.providers,
           contextId,
         );
-        return contextInstance[listenerMethodKey].call(
+        return this.wrapFunctionInTryCatchBlocks(
           contextInstance,
-          ...args,
+          listenerMethodKey,
+          args,
         );
       },
       options,
@@ -168,4 +172,16 @@ export class EventSubscribersLoader
 
     this.moduleRef.registerRequestByContextId(payloadObjectOrArray, contextId);
   }
+
+  private async wrapFunctionInTryCatchBlocks(
+    instance: Record<string, any>,
+    methodKey: string,
+    args: unknown[],
+  ) {
+    try {
+      return await instance[methodKey].call(instance, ...args);
+    } catch (e) {
+      this.logger.error(e);
+    }
+  }
 }

tests/e2e/module-e2e.spec.ts

@@ -122,6 +122,26 @@ describe('EventEmitterModule - e2e', () => {
     expect(customConsumer.isEmitted).toBeTruthy();
   });
 
+  it('should be able to gracefully recover when an unexpected error occurs from provider', async () => {
+    const eventsConsumerRef = app.get(EventsProviderConsumer);
+    await app.init();
+
+    const emitter = app.get(EventEmitter2);
+    const result = emitter.emit('error-handling.provider');
+
+    expect(eventsConsumerRef.errorHandlingCalls).toEqual(1);
+    expect(result).toBeTruthy();
+  });
+
+  it('should be able to gracefully recover when an unexpected error occurs from request scoped', async () => {
+    await app.init();
+
+    const eventEmitter = app.get(EventEmitter2);
+    const result = eventEmitter.emit('error-handling.request-scoped');
+
+    expect(result).toBeTruthy();
+  });
+
   afterEach(async () => {
     await app.close();
   });

tests/src/events-provider.consumer.ts

@@ -5,6 +5,7 @@ import { OnEvent } from '../../lib';
 export class EventsProviderConsumer {
   public eventPayload = {};
   public stackedEventCalls = 0;
+  public errorHandlingCalls = 0;
 
   @OnEvent('test.*')
   onTestEvent(payload: Record<string, any>) {
@@ -16,4 +17,10 @@ export class EventsProviderConsumer {
   onStackedEvent() {
     this.stackedEventCalls++;
   }
+
+  @OnEvent('error-handling.provider')
+  onErrorHandlingEvent() {
+    this.errorHandlingCalls++;
+    throw new Error('This is a test error');
+  }
 }

tests/src/events-provider.request-scoped.consumer.ts

@@ -21,4 +21,9 @@ export class EventsProviderRequestScopedConsumer {
 
   @OnEvent('string.*')
   onStringPayloadEvent() {}
+
+  @OnEvent('error-handling.request-scoped')
+  onErrorHandlingEvent() {
+    throw new Error('This is a test error');
+  }
 }