setup-polly-jest

Disclaimer

This is proof of concept created as a demo of the approach with the goal to suggest it as a core feature in the PollyJS library. If this will happen, this package will be deprecated with a minor release and a notice how to migrate

Overview

setup-polly-jest is a helper method which after being called will set up new PollyJS instance before each test case.

This helper behaves almost the same way as built-in Mocha or QUnit helpers for PollyJS. There are a couple of differences though:

• As jest tests usually use arrow functions and in general using this in jest tests is not a common thing, this library will return context with polly as a property set to it instead of setting polly as a property on the this context
• beforeEach hook that creates new polly instance will always be the first in the chain of test case hooks
• afterEach hook that stops polly and removes polly from the context will always be the last in the chain of test case hooks
• Context also gives you an access to clearPolly method, that can remove polly from the test runner at any time (by default polly will be removed in the afterAll hook)

Installation

This library has a peer dependency on @pollyjs/core

npm install --save-dev @pollyjs/core @gribnoysup/setup-polly-jest

Usage

// index.test.js

import FSPersister from '@pollyjs/persister-fs';
import FetchAdapter from '@pollyjs/adapter-fetch';

import { setupPolly } from '@gribnoysup/setup-polly-jest';

const context = setupPolly({
  adapters: [FetchAdapter],
  persister: FSPersister,
  persisterOptions: {
    fs: {
      recordingsDir: '__recordings__'
    }
  }
});

describe('test with polly', () => {
  it('should init polly and proxy the request with it', async () => {
    const response = await fetch(
      'https://jsonplaceholder.typicode.com/posts/1'
    );

    expect(await response.json()).toHaveProperty('id', 1);
  });

  it('should configure polly to record failed requests', async () => {
    context.polly.configure({ recordFailedRequests: true });

    const response = await fetch(
      'https://jsonplaceholder.typicode.com/posts/99999'
    );

    expect(response).toHaveProperty('ok', false);
    expect(response).toHaveProperty('status', 404);
  });

  it('should unset polly from the tests runner', async () => {
    await context.clearPolly();

    /* this will send a real request to the server */
    const response = await fetch(
      'https://jsonplaceholder.typicode.com/posts/2'
    );

    expect(await response.json()).toHaveProperty('id', 2);
  });
});

ℹ️  For real-world example, check out tests in this repo

LICENCE

ISC