test.ts

import { MovieShowingsComponent } from './movie-showings.component';
import { cold, getTestScheduler } from 'jasmine-marbles';

describe('MovieShowingsComponent', () => {
  it('should not have a race condition', () => {
    const backend = jasmine.createSpyObj('backend', ['getShowings']);
    const cmp = new MovieShowingsComponent(backend);

    backend.getShowings.and.returnValue(cold('--x|', {x: ['10am']}));
    cmp.selectMovie('After the Storm');

    backend.getShowings.and.returnValue(cold('-y|', {y: ['11am']}));
    cmp.selectMovie('Paterson');

    // this will flush all observables
    getTestScheduler().flush();

    expect(cmp.movieTitle).toEqual('Paterson');
    expect(cmp.showings).toEqual(['11am']); // This will fail because showings is ['10am'].
  });
});