nest/integration/nest-application/sse/e2e/express.spec.ts

import { NestExpressApplication } from '@nestjs/platform-express';
import { Test } from '@nestjs/testing';
import { expect } from 'chai';
import { EventSource } from 'eventsource';
import { AppModule } from '../src/app.module';

describe('Sse (Express Application)', () => {
  let app: NestExpressApplication;
  let eventSource: EventSource;

  describe('without forceCloseConnections', () => {
    beforeEach(async () => {
      const moduleFixture = await Test.createTestingModule({
        imports: [AppModule],
      }).compile();

      app = moduleFixture.createNestApplication<NestExpressApplication>();

      await app.listen(3000);
      const url = await app.getUrl();

      eventSource = new EventSource(url + '/sse', {
        fetch: (input, init) =>
          fetch(input, {
            ...init,
            headers: {
              ...init?.headers,
              connection: 'keep-alive',
            },
          }),
      });
    });

    // The order of actions is very important here. When not using `forceCloseConnections`,
    // the SSe eventsource should close the connections in order to signal the server that
    // the keep-alive connection can be ended.
    afterEach(async () => {
      eventSource.close();

      await app.close();
    });

    it('receives events from server', done => {
      eventSource.addEventListener('message', event => {
        expect(JSON.parse(event.data)).to.eql({
          hello: 'world',
        });
        done();
      });
    });
  });

  describe('with forceCloseConnections', () => {
    beforeEach(async () => {
      const moduleFixture = await Test.createTestingModule({
        imports: [AppModule],
      }).compile();

      app = moduleFixture.createNestApplication<NestExpressApplication>({
        forceCloseConnections: true,
      });

      await app.listen(3000);
      const url = await app.getUrl();

      eventSource = new EventSource(url + '/sse', {
        fetch: (input, init) =>
          fetch(input, {
            ...init,
            headers: {
              ...init?.headers,
              connection: 'keep-alive',
            },
          }),
      });
    });

    afterEach(async () => {
      await app.close();

      eventSource.close();
    });

    it('receives events from server', done => {
      eventSource.addEventListener('message', event => {
        expect(JSON.parse(event.data)).to.eql({
          hello: 'world',
        });
        done();
      });
    });
  });
});