pollyjs README

The project's README from github.com/Netflix/pollyjs. As one markdown file: README.md.

Polly.JS

Record, Replay, and Stub HTTP Interactions

Build Status license

Polly.JS is a standalone, framework-agnostic JavaScript library that enables recording, replaying, and stubbing of HTTP interactions. By tapping into multiple request APIs across both Node & the browser, Polly.JS is able to mock requests and responses with little to no configuration while giving you the ability to take full control of each request with a simple, powerful, and intuitive API.

Interested in contributing or just seeing Polly in action? Head over to CONTRIBUTING.md to learn how to spin up the project!

Why Polly?

Keeping fixtures and factories in parity with your APIs can be a time consuming process. Polly alleviates this process by recording and maintaining actual server responses while also staying flexible.

Features

Getting Started

Check out the Quick Start documentation to get started.

Usage

Let's take a look at what an example test case would look like using Polly.

import { Polly } from '@pollyjs/core';
import XHRAdapter from '@pollyjs/adapter-xhr';
import FetchAdapter from '@pollyjs/adapter-fetch';
import RESTPersister from '@pollyjs/persister-rest';

/*
  Register the adapters and persisters we want to use. This way all future
  polly instances can access them by name.
*/
Polly.register(XHRAdapter);
Polly.register(FetchAdapter);
Polly.register(RESTPersister);

describe('Netflix Homepage', function () {
  it('should be able to sign in', async function () {
    /*
      Create a new polly instance.

      Connect Polly to both fetch and XHR browser APIs. By default, it will
      record any requests that it hasn't yet seen while replaying ones it
      has already recorded.
    */
    const polly = new Polly('Sign In', {
      adapters: ['xhr', 'fetch'],
      persister: 'rest'
    });
    const { server } = polly;

    /* Intercept all Google Analytic requests and respond with a 200 */
    server
      .get('/google-analytics/*path')
      .intercept((req, res) => res.sendStatus(200));

    /* Pass-through all GET requests to /coverage */
    server.get('/coverage').passthrough();

    /* start: pseudo test code */
    await visit('/login');
    await fillIn('email', '[email protected]');
    await fillIn('password', '@pollyjs');
    await submit();
    /* end: pseudo test code */

    expect(location.pathname).to.equal('/browse');

    /*
      Calling `stop` will persist requests as well as disconnect from any
      connected browser APIs (e.g. fetch or XHR).
    */
    await polly.stop();
  });
});

The above test case would generate the following HAR file which Polly will use to replay the sign-in response when the test is rerun:

{
  "log": {
    "_recordingName": "Sign In",
    "browser": {
      "name": "Chrome",
      "version": "67.0"
    },
    "creator": {
      "name": "Polly.JS",
      "version": "0.5.0",
      "comment": "persister:rest"
    },
    "entries": [
      {
        "_id": "06f06e6d125cbb80896c41786f9a696a",
        "_order": 0,
        "cache": {},
        "request": {
          "bodySize": 51,
          "cookies": [],
          "headers": [
            {
              "name": "content-type",
              "value": "application/json; charset=utf-8"
            }
          ],
          "headersSize": 97,
          "httpVersion": "HTTP/1.1",
          "method": "POST",
          "postData": {
            "mimeType": "application/json; charset=utf-8",
            "text": "{\"email\":\"[email protected]\",\"password\":\"@pollyjs\"}"
          },
          "queryString": [],
          "url": "https://netflix.com/api/v1/login"
        },
        "response": {
          "bodySize": 0,
          "content": {
            "mimeType": "text/plain; charset=utf-8",
            "size": 0
          },
          "cookies": [],
          "headers": [],
          "headersSize": 0,
          "httpVersion": "HTTP/1.1",
          "redirectURL": "",
          "status": 200,
          "statusText": "OK"
        },
        "startedDateTime": "2018-06-29T17:31:55.348Z",
        "time": 11,
        "timings": {
          "blocked": -1,
          "connect": -1,
          "dns": -1,
          "receive": 0,
          "send": 0,
          "ssl": -1,
          "wait": 11
        }
      }
    ],
    "pages": [],
    "version": "1.2"
  }
}

Prior Art

The "Client Server" API of Polly is heavily influenced by the very popular mock server library pretender. Pretender supports XHR and Fetch stubbing and is a great lightweight alternative to Polly if your project does not require persisting capabilities or Node adapters.

Thank you to all contributors especially the maintainers: trek, stefanpenner, and xg-wang.

Contributors

License

Copyright (c) 2018 Netflix, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

pollyjs (Netflix/pollyjs)

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Pollyjs
What is this?It's Polly.JS, a JavaScript library from Netflix that records, replays, and stubs HTTP interactions, so your test suite doesn't need a live API to run against.
Is this a library I add to my tests, or a mock server I have to run?A library you plug into your tests, not a separate server. It hooks the request APIs your code already uses in Node and the browser and mocks responses with little to no configuration.
How do I wire it into my test suite?Install the @pollyjs packages from npm and register its helper in your test setup, following the Quick Start docs the README links to.
Which test runners does it support out of the box?It ships first-class helpers for Mocha and QUnit and stays framework-agnostic everywhere else — no other runtime or backend required.
Does it work for browser tests too, or only in Node?Both — Node and browser support is the first listed feature, so the same record/replay setup covers server-side and in-browser tests.
Can I use it in commercial projects?Yes — it's Apache-2.0, a permissive license (copyright Netflix, Inc.), with no strings attached for commercial use.
How does the record and replay cycle actually work?On the first run Polly records your suite's real HTTP interactions into a HAR file; every rerun replays that recording instead of hitting the server, giving fast, deterministic, accurate tests.
Where do the recordings get stored?In Node they're written to disk; in the browser they go to Local Storage. Either way Polly picks them up on the next run.
Can I fake error or loading states without re-recording?Yes — the client-side server lets you intercept and modify requests and responses to simulate states like loading or errors, and you can even slow down or speed up time to test latency behavior.
How is it different from the mock server Pretender?Polly's Client Server API was heavily influenced by Pretender, which the README calls a great lightweight alternative if you don't need persisting recordings or Node adapters.
What are similar projects?msw, Mock, nock, react-testing-library, jsdom, testify, mockito, jest
Which topics is it in?record, mocking, testing-tools, test-automation, unit-testing, http, javascript-library, testing, browser, web-development, npm, frontend
Creator
Netflix
Size
3.6 MB
Stars
10.3K
Updated
CommitMay 31
Age
8y
Commits · 90 Days