feat(rabbitmq): execution context check utility

convenience function to check whether the current handler in an execution context is related to
RabbitMQ

re #204

integration/rabbitmq/e2e/execution-context.e2e-spec.ts

@@ -0,0 +1,84 @@
+import {
+  AmqpConnection,
+  isRabbitContext,
+  RabbitMQModule,
+  RabbitSubscribe,
+} from '@golevelup/nestjs-rabbitmq';
+import { CallHandler, ExecutionContext, NestInterceptor } from '@nestjs/common';
+import { INestApplication, Injectable } from '@nestjs/common';
+import { Test } from '@nestjs/testing';
+
+const interceptorHandler = jest.fn();
+
+const exchange = 'contextExchange';
+const queue = 'contextQueue';
+
+@Injectable()
+class TestInterceptor implements NestInterceptor {
+  intercept(context: ExecutionContext, next: CallHandler<any>) {
+    const shouldSkip = isRabbitContext(context);
+    if (shouldSkip) {
+      return next.handle();
+    }
+
+    interceptorHandler('invoked');
+    return next.handle();
+  }
+}
+
+@Injectable()
+class SubscribeService {
+  @RabbitSubscribe({
+    exchange,
+    routingKey: '#',
+    queue,
+  })
+  handleSubscribe(message: object) {
+    console.log(`RECEIVED MESSAGE: ${message}`);
+  }
+}
+
+describe('Rabbit Subscribe Without Register Handlers', () => {
+  let app: INestApplication;
+  let amqpConnection: AmqpConnection;
+
+  const rabbitHost = process.env.NODE_ENV === 'ci' ? 'rabbit' : 'localhost';
+  const uri = `amqp://rabbitmq:rabbitmq@${rabbitHost}:5672`;
+
+  beforeAll(async () => {
+    const moduleFixture = await Test.createTestingModule({
+      providers: [SubscribeService, TestInterceptor],
+      imports: [
+        RabbitMQModule.forRoot(RabbitMQModule, {
+          exchanges: [
+            {
+              name: exchange,
+              type: 'topic',
+            },
+          ],
+          uri,
+          connectionInitOptions: { wait: true, reject: true, timeout: 3000 },
+        }),
+      ],
+    }).compile();
+
+    app = moduleFixture.createNestApplication();
+    amqpConnection = app.get<AmqpConnection>(AmqpConnection);
+    app.useGlobalInterceptors(new TestInterceptor());
+    await app.init();
+  });
+
+  afterAll(async () => {
+    await app.close();
+  });
+
+  it('should recognize a rabbit handler execution context and allow for interceptors to be skipped', async (done) => {
+    await amqpConnection.publish(exchange, 'x', `test-message`);
+    expect.assertions(1);
+
+    setTimeout(() => {
+      expect(interceptorHandler).not.toHaveBeenCalled();
+      done();
+    }, 100);
+  });
+});

packages/rabbitmq/src/index.ts

@@ -5,3 +5,4 @@ export * from './rabbitmq.constants';
 export * from './rabbitmq.decorators';
 export * from './rabbitmq.interfaces';
 export * from './rabbitmq.module';
+export * from './rabbitmq.helpers';

packages/rabbitmq/src/rabbitmq.helpers.ts

@@ -0,0 +1,7 @@
+import { ExecutionContext } from '@nestjs/common';
+import { RABBIT_HANDLER } from './rabbitmq.constants';
+
+export const isRabbitContext = (executionContext: ExecutionContext) => {
+  const handler = executionContext.getHandler();
+  return Reflect.getMetadataKeys(handler).includes(RABBIT_HANDLER);
+};