subscribe-on-init.decorator.spec.ts

import { OnDestroy, OnInit } from '@angular/core';
import { Observable } from 'rxjs';

import { MarbleTestScheduler } from '../testing/marbles';

import { SubscribeOnInit } from './subscribe-on-init.decorator';

describe('@SubscribeOnInit', () => {
  const VALUES = { a: 'a' };
  let scheduler: MarbleTestScheduler<string>;

  class PropertyTestClass<T extends Observable<any>> implements OnInit, OnDestroy {
    @SubscribeOnInit()
    public readonly obs$: T;

    public constructor(
      obs$: T,
      private readonly initSpy = (): void => undefined,
      private readonly destroySpy = (): void => undefined
    ) {
      this.obs$ = obs$;
    }

    public ngOnInit(): void {
      this.initSpy();
    }

    public ngOnDestroy(): void {
      this.destroySpy();
    }
  }

  beforeEach(() => {
    scheduler = MarbleTestScheduler.create(VALUES);
  });

  it('should subscribe on init and unsubscribe on destroy', () =>
    scheduler.run(({ cold, expectSubscriptions }) => {
      const obj = new PropertyTestClass(cold('a'));

      obj.ngOnInit();
      scheduler.schedule(() => obj.ngOnDestroy(), scheduler.createTime('---|'));

      expectSubscriptions(obj.obs$.subscriptions).toBe('^!');
    }));

  it('should be tied only to object instances', () =>
    scheduler.run(({ cold, expectSubscriptions }) => {
      const obj1 = new PropertyTestClass(cold('a'));
      const obj2 = new PropertyTestClass(cold('a'));

      obj1.ngOnInit();
      obj2.ngOnInit();
      scheduler.schedule(() => obj1.ngOnDestroy(), scheduler.createTime('--|'));
      scheduler.schedule(() => obj2.ngOnDestroy(), scheduler.createTime('----|'));

      expectSubscriptions(obj1.obs$.subscriptions).toBe('^--!');
      expectSubscriptions(obj2.obs$.subscriptions).toBe('^----!');
    }));

  it('should call original ngOnInit', () =>
    scheduler.run(({ cold }) => {
      const obs$ = cold('a');
      const initSpy = jasmine.createSpy('ngOnInit');
      const obj = new PropertyTestClass(obs$, initSpy);

      obj.ngOnInit();

      expect(initSpy).toHaveBeenCalled();
    }));