Using marble testing rxjs5 method inside another project

Question

I have a webapp project which uses rxjs5 to implement a flux and I am currently looking for solutions to write unit tests on it.

In fact, I have implemented custom observables inside, for example :

function getActivityObservable(events, timeout) {
  return Observable.create((observer) => {
    const deb = debounce(() => observer.next(false), timeout || DEFAULT_TIMEOUT);
    const sub = events.subscribe((e) => {
      if (!e) {
        deb.cancel();
        observer.next(false);
      } else {
        observer.next(true);
        deb(e);
      }
    });

    return () => {
      if (sub) sub.unsubscribe();
      if (deb) deb.cancel();
    };
  }).distinctUntilChanged();
}

I would like to test it using the marble testing way and write something like (i took a sample example from rxjs repository)

  describe("getActivityObservable", () => {
    it("should debounce by selector observable", () => {
      const e1 =   hot("--a--bc--d----|");
      const e1subs =   "^             !";
      const expected = "----a---c--d--|";

      expectObservable(e1.debounce(getTimerSelector(20))).toBe(expected);
      expectSubscriptions(e1.subscriptions).toBe(e1subs);
    });
  });

My question is:

Is it possible to use marble testing method (with operators like hot, cold and so on...) outside the rxjs5 project. I don't figure out how to use this nice tool in my project.

Thank you for your help.

Answer 1

You can but as Ben comment: "it's not very ergonomic".

I'm using mocha and monkey patching it:

const isEqual = require('lodash.isequal');
const TestScheduler = require('rxjs/testing/TestScheduler').TestScheduler;

const assertDeepEqualFrame = (actual, expected) => {
  if (!isEqual(actual, expected)) {
    throw new Error('Frames not equal!');
  }
}

const oit = global.it;
global.it = function(description, cb, timeout) {
  if (cb.length === 0) {
    oit(description, function() {
      global.rxTestScheduler = new TestScheduler(assertDeepEqualFrame);
      cb();
      global.rxTestScheduler.flush();
    });
  } else { // async test
    oit.apply(this, arguments);
  }
};

I have taking a lot of inspirations from ngrx/store and especially this file: https://github.com/ngrx/store/blob/master/spec/helpers/test-helper.ts

and then can I write my test like:

it('should filter with an always-true predicate', () => {
  const source = hot('-1--2--^-3-4-5-6--7-8--9--|');
  const expected =          '--3-4-5-6--7-8--9--|';
  const predicate = () => { return true; };

  expectObservable(source.filter(predicate)).toBe(expected);
});

Edit You can see how I monkey patch it here: https://github.com/tjoskar/ng2-lazyload-image/blob/5e1c64a3611530ce26857a566b2d76dff890a3c5/test/helpers/test-helper.ts