RxJS marble test fail with operator delay()

Question

I have the following test, it works...

import { TestScheduler } from 'rxjs/internal/testing/TestScheduler';

describe('RxJx', () => {

  const testScheduler = new TestScheduler((actual, expected) => {

    console.log('works here?');

    console.log(actual);
    console.log(expected);

    expect(actual).toEqual(expected);
  });

  it('rxjs delay should work', () => {


    testScheduler.run((helpers) => {
      const {cold, expectObservable} = helpers;
      const sequence1 = cold('-a--b--c---|', {a: 2, b: 2, c: 10});
      // const sequence = '- 1ms a--b--c---|';
      const sequence = '-a--b--c---|';

      expectObservable(
        // sequence1.pipe(delay(1))
        sequence1
      ).toBe(sequence, {a: 2, b: 2, c: 10});

    });

  });

});

result screenshot...

but as soon as I add a delay operator, the code stops working.

import { TestScheduler } from 'rxjs/internal/testing/TestScheduler';
import { delay } from 'rxjs';

describe('RxJx', () => {

  const testScheduler = new TestScheduler((actual, expected) => {

    console.log('works here?');

    console.log(actual);
    console.log(expected);

    expect(actual).toEqual(expected);
  });

  it('rxjs delay should work', () => {


    testScheduler.run((helpers) => {
      const {cold, expectObservable} = helpers;
      const sequence1 = cold('-a--b--c---|', {a: 2, b: 2, c: 10});
      const sequence = ' 1s -a--b--c---|';
      // const sequence = '-a--b--c---|';

      expectObservable(
        sequence1.pipe(delay(1000))
        // sequence1
      ).toBe(sequence, {a: 2, b: 2, c: 10});

    });

  });

});

TestScheduler gets confusing result.

result screenshot

Please help me figure out what am I doing wrong?

If I do so, the tests pass...

const sequence1 = cold('-a--b--c', {a: 2, b: 2, c: 10});
const sequence = ' 1s -a--b--c';

result screenshot...

Angular 15, build in test with RxJs

RxJS marble test fail with operator delay()

0 Answers0