@spotify/polly-jest-presets
v3.1.1
Published
Presets for Jest that make Polly.js plug-and-play
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Readme
polly-jest-presets
An opinionated configuration and wrapper around Polly and setup-polly-jest to have automatic recording and playback of network requests made during your Jest tests.
Note: Polly Jest Presets bundles in all necessary Polly packages to make the setup as easy as possible for a typical Node-based web app. It uses File persister to store recordings locally. Therefore, there's no need to install Polly or Polly Jest bindings separately in your project after including this preset.
Packages included:
"@pollyjs/adapter-node-http": "^2.6.0",
"@pollyjs/core": "^2.6.0",
"@pollyjs/persister-fs": "^2.6.0",
"setup-polly-jest": "^0.5.2",
Usage
Install the preset as a dev dependency:
yarn add @spotify/polly-jest-presets -D
Add the preset to your Jest config (by default jest.config.js
), in the setupFilesAfterEnv
:
{
"setupFilesAfterEnv": ["@spotify/polly-jest-presets"]
}
Or import in an individual test.
// ./my.test.js
import '@spotify/polly-jest-presets';
Getting Started
To test it out, make a network request in one of your tests.
import '@spotify/polly-jest-presets';
// `yarn add -D node-fetch` for this demo
import fetch from 'node-fetch';
describe('a dummy test', () => {
it('fetches something', async () => {
const resp = await fetch('https://reqres.in/api/users?page=2');
const payload = await resp.json();
expect(payload.data.length).toBeGreaterThan(1);
});
});
First, you need to run the tests with the POLLY_MODE
environment variable set to record
. This will tell Polly that you intend for all of the requests to record in this test run.
POLLY_MODE="record" jest
You should now see a __recordings__
directory next to your test file. It should contain a .har
file which shows the request we made within the it block.
To test that playback works, disconnect your internet on your machine and run:
POLLY_MODE="replay" jest
The test still passes! Note: the default POLLY_MODE is replay
.
Configuration and API usage
If you want to override Polly configuration, you can add configuration to globals.pollyConfig
in the Jest config:
{
"globals": {
"pollyConfig": {
"expiresIn": "3 months"
}
}
}
See all of the valid Polly options in the Polly documentation.
You may also want to get at the global Polly instance. You can import it:
// if you need access to the pollyContext
import { pollyContext } from '@spotify/polly-jest-presets';
pollyContext.polly.server
.get('/series')
.intercept((req, res) => res.sendStatus(200));
See all of the Polly API methods in the Polly documentation.
Opinions
This preset has a few opinions baked in. All of these are overridable by setting the globals.pollyConfig
in your Jest config.
Expire recordings often
We think it's safer to expire recordings frequently. The default expiresIn
is set to "14d"
in this preset. By default, expiryStrategy
is configured to warn
.
Explicit recording only (no recordIf*
)
We think it makes more sense to avoid recording in the background for test authoring to avoid unexpected changes to checked in .har files. Because of this, we have set all of the recordIf*
config values to false. This means that your tests will fail when you first write them if you don't override POLLY_MODE
.
Contributing
See CONTRIBUTING guidelines.