chai_rxjs.md

layout	permalink	pluginName
plugin	plugins/chai-rxjs/	chai-rxjs

Chai Assertions for RxJS Observables

ChaiRx extends Chai with a simple utility method emit for testing emits from an RxJS Observable stream using the Rx.TestScheduler.

import Rx from 'rx';
import chai from 'chai';
import chaiRx from 'chai-rx';

chai.use(chaiRx);

const { onNext, onCompleted } = Rx.ReactiveTest;
const scheduler = new Rx.TestScheduler();

const xs = scheduler.createHotObservable(
  onNext(150, 1),
  onNext(210, 2),
  onNext(220, 3),
  onCompleted(230)
);

// Note we'll start at 200 for subscribe, hence missing the 150 mark
const output = scheduler.startScheduler(() => xs.map(x => x * x), {
  created: 100,
  subscribed: 200,
  disposed: 300
});

expect(output).to.emit([
  onNext(210, 4),
  onNext(220, 9),
  onCompleted(230)
]);

Usage

expect / should syntax

const xs = scheduler.createHotObservable(onNext(250, { 'foo': 'bar' }), onError(300, new Error('An error')));
const output = scheduler.startScheduler(() => xs);

// expect
expect(output).to.emit([
  onNext(250, { 'foo': 'bar' }),
  onError(300, ({error}) => error.message === 'An error')
]);

// should
output.should.emit([
  onNext(250, { 'foo': 'bar' }),
  onError(300, ({error}) => error.message === 'An error')
]);

Language chains

const const xs = scheduler.createHotObservable(onNext(250));
const output = scheduler.startScheduler(() => xs);

// with `not`
expect(output).to.not.emit([
  onNext(300)
]);

Installation

npm install chai-rx

ES6 Imports

import chai from 'chai';
import chaiRx from 'chai-rx';

chai.use(chaiRx);

AMD

var chai = require('chai');
var chaiRx = require('chai-rx');

chai.use(chaiRx);

<script> tag

If you include ChaiRx directly with a <script> tag, after the one for Chai itself, then it will automatically plug in to Chai and be ready for use:

<script src="chai.js"></script>
<script src="chai-rx.js"></script>