RxJS Observable Matchers

Custom RxJS Observable matchers for Jest and Jasmine

Overview

What

A small set of test matchers for testing RxJS Observables, compatible with all versions of Jasmine and Jest.

Why

When testing simple RxJS observables, RxJS Marble Testing may be too verbose. This set of test matchers may provide a more simple API and reduce boilerplate code.

Limitations

The matchers provided in this package only support synchronous streams.

Testing asynchronous Observables is not (yet) supported!

Installation 🌩

npm

npm install @dirkluijk/observable-matchers --save-dev

yarn

yarn add @dirkluijk/observable-matchers --dev

API 📝

Asymmetric Matchers (recommended)

import { of } from 'rxjs';
import {
    next,
    completed,
    emptyObservable,
    completedObservable,
    failedObservable,
    observable,
    observableWithSize
} from '@dirkluijk/observable-matchers';

const completed$ = of(10, 20, 30);

expect(completed$).toEqual(observable(
    next(10),
    next(20),
    next(30),
    completed()
));
expect(completed$).not.toEqual(emptyObservable());
expect(completed$).toEqual(completedObservable());
expect(completed$).not.toEqual(failedObservable());
expect(completed$).toEqual(observableWithSize(3));

Matchers

import { of } from 'rxjs';
import { next, completed } from '@dirkluijk/observable-matchers';
import '@dirkluijk/observable-matchers/matchers';

const completed$ = of(10, 20, 30);

expect(completed$).toBeObservable([
    next(10),
    next(20),
    next(30),
    completed()
]);
expect(completed$).not.toBeEmpty();
expect(completed$).toBeCompleted();
expect(completed$).not.toBeFailed();
expect(completed$).toBeOfSize(3);

Record utility

Sometimes a stream does not replay its events. In order to capture its events, you can use the provided record() function.

import { record, emptyObservable } from '@dirkluijk/observable-matchers';
import '@dirkluijk/observable-matchers/matchers';

const recorded$ = record(someStream());

triggerEvents();

expect(recorded$).not.toEqual(emptyObservable());
// or 
expect(recorded$).not.toBeEmpty();

Usage 🕹

In order to use the asymmetric matchers (e.g. toEqual(observable(...)), toEqual(completedObservable())), you just need to import them as pure functions:

import { completedObservable, observable } from '@dirkluijk/observable-matchers';

In order to use the matchers (e.g. toBeObservable, toBeCompleted), you need to register the matchers and import the typings as follows:

import '@dirkluijk/observable-matchers/matchers';

Please note that the use of matchers may collide with matchers from other libraries.

Contributors ✨

Thanks goes to these wonderful people (emoji key):

This project follows the all-contributors specification. Contributions of any kind welcome!