Awesome

playwright-network-cache

Speed up Playwright tests by caching network requests on the filesystem.

✨ Features

• Automatically cache network requests during test execution
• Save responses to the filesystem in a clear, organized structure
• Modify cached responses dynamically during runtime
• Reuse cached data across multiple test runs
• Configure TTL to automatically refresh the cache and keep responses up-to-date
• View response bodies in a pretty formatted JSON
• No need for manual mocks management
• No mess with the HAR format — see motivation

Example of cache structure:

.network-cache
└── example.com
    └── api-cats
        └── GET
            ├── headers.json
            └── body.json

Index

• Installation
• Basic usage
• Examples
  • Invalidate cache once in a hour
  • Modify cached response
  • Disable cache
  • Force cache update
  • Auto-cache request for all tests
  • Additional match by HTTP status
  • Additional match by request fields
  • Split cache by test title
  • Split cache by request URL params
  • Split cache by request body
  • Change base dir
  • Multi-step cache in complex scenarios
• API
  • Constructor
  • Methods
  • Options
• Debug
• Motivation
• Alternatives
• Changelog
• Feedback
• License

Installation

Install from npm:

npm i -D playwright-network-cache

Basic usage

1. Setup cacheRoute fixture

Extend Playwright's test instance with cacheRoute fixture:

// fixtures.ts
import { test as base } from '@playwright/test';
import { CacheRoute } from 'playwright-network-cache';

type Fixtures = {
  cacheRoute: CacheRoute;
};

export const test = base.extend<Fixtures>({
  cacheRoute: async ({ page }, use) => {
    await use(new CacheRoute(page, { /* cache options */ }));
  },
});

2. Use cacheRoute inside test

For example, to cache a GET request to https://example.com/api/cats:

// test.ts
test('test', async ({ page, cacheRoute }) => {
  await cacheRoute.GET('https://example.com/api/cats*');
  // ... perform usual test actions
});

On the first run, the test will hit real API and store the response on the filesystem:

.network-cache
└── example.com
    └── api-cats
        └── GET
            ├── headers.json
            └── body.json

All subsequent test runs will re-use cached response and execute much faster. You can invalidate that cache by manually deleting the files. Or provide ttlMinutes option to hit real API once in some period of time.

You can call cacheRoute.GET|POST|PUT|PATCH|DELETE|ALL to cache routes with respective HTTP method. Url can contain * or ** to match url segments and query params, see url pattern.

To catch requests targeting your own app APIs, you can omit hostname in url:

test('test', async ({ page, cacheRoute }) => {
  await cacheRoute.GET('/api/cats*');
  // ...
});

Default cache path is:

{baseDir}/{hostname}/{pathname}/{httpMethod}/{extraDir}/{httpStatus}

See more examples below or check configuration options.

Examples

Invalidate cache once in a hour

To keep response data up-to-date, you can automatically invalidate cache after configured time period. Set ttlMinutes option to desired value in minutes:

test('test', async ({ page, cacheRoute }) => {
  await cacheRoute.GET('/api/cats', {
    ttlMinutes: 60 // hit real API once in a hour
  });
  // ...
});

Modify cached response

You can modify the cached response by setting the modify option to a custom function. In this function, you retrieve the response data, make your changes, and then call route.fulfill with the updated data.

test('test', async ({ page, cacheRoute }) => {
  await cacheRoute.GET('/api/cats', {
    modify: async (route, response) => {
      const json = await response.json();
      json[0].name = 'Kitty-1';
      await route.fulfill({ json });
    }
  });
  // ...
});

For modifying JSON responses, there is a helper option modifyJSON:

test('test', async ({ page, cacheRoute }) => {
  await cacheRoute.GET('/api/cats', {
    modifyJSON: (json) => {
      json[0].name = 'Kitty';
    },
  });
  // ...
});

modifyJSON can modify response json in-place (like above) or return some result, which will overwrite the original data.

Disable cache

To disable cache in a single test, set cacheRoute.options.noCache to true:

test('test', async ({ page, cacheRoute }) => {
  cacheRoute.options.noCache = true;
  await cacheRoute.GET('/api/cats'); // <- this will not cache the request
  // ...
});

To disable cache in all tests, set the noCache option to true in the fixture:

export const test = base.extend<{ cacheRoute: CacheRoute }>({
  cacheRoute: async ({ page }, use, testInfo) => {
    await use(new CacheRoute(page, {
      noCache: true
    }));
  }
});

Note: When cache is disabled, modify functions still run

Force cache update

To force updating cache files for a single test, set cacheRoute.options.forceUpdate to true:

test('test', async ({ page, cacheRoute }) => {
  cacheRoute.options.forceUpdate = true;
  await cacheRoute.GET('/api/cats');
  // ...
});

To force updating cache files for all tests, set the forceUpdate option to true in the fixture:

export const test = base.extend<{ cacheRoute: CacheRoute }>({
  cacheRoute: async ({ page }, use, testInfo) => {
    await use(new CacheRoute(page, {
      forceUpdate: true
    }));
  }
});

Auto-cache request for all tests

You can setup caching of some request for all tests. Define cacheRoute as auto fixture and setup cached routes:

export const test = base.extend<{ cacheRoute: CacheRoute }>({
  cacheRoute: [async ({ page }, use) => {
    const cacheRoute = new CacheRoute(page);
    await cacheRoute.GET('/api/cats');
    await use(cacheRoute);
  }, { auto: true }]
});

Additional match by HTTP status

By default, only responses with 2xx status are considered valid and stored in cache. To test error responses, provide additional httpStatus option to cache route:

test('test', async ({ page, cacheRoute }) => {
  await cacheRoute.GET('/api/cats', { 
    httpStatus: 500 
  });
  // ...
});

Now error response will be cached in the following structure:

.network-cache
└── example.com
    └── api-cats
        └── GET
            └── 500
                ├── headers.json
                └── body.json

Additional match by request fields

By default, requests are matched by:

HTTP method + URL pattern + (optionally) HTTP status 

If you need to match by other request fields, provide custom function to match option. Example of matching GET requests with query param /api/cats?foo=bar:

test('test', async ({ page, cacheRoute }) => {
  await cacheRoute.GET('/api/cats*', { 
    match: req => new URL(req.url()).searchParams.get('foo') === 'bar'
  });
  // ...
});

Notice * in /api/cats* to match query params

Split cache by test title

By default, cached responses are stored in a shared directory and re-used across tests. If you want to isolate cache files for a particular test, utilize cacheRoute.options.extraDir - an array of extra directories to be inserted into the cache path:

test('test', async ({ page, cacheRoute }) => {
  cacheRoute.options.extraDir.push('custom-test');
  await cacheRoute.GET('/api/cats');
  // ...
});

Generated cache structure:

.network-cache
└── example.com
    └── api-cats
        └── GET
            └── custom-test       # <- extra directory
                ├── headers.json
                └── body.json

You can freely transform extraDir during the test and create nested directories if needed.

To automatically store cache files in a separate directories for each test, you can set extraDir option in a fixture setup:

export const test = base.extend<{ cacheRoute: CacheRoute }>({
  cacheRoute: async ({ page }, use, testInfo) => {
    await use(new CacheRoute(page, {
      extraDir: testInfo.title  // <- use testInfo.title as a unique extraDir
    }));
  }
});

After running two tests with titles custom test 1 and custom test 2, the generated structure is:

.network-cache
└── example.com
    └── api-cats
        └── GET
            ├── custom-test-1
            │   ├── headers.json
            │   └── body.json
            └── custom-test-2
                ├── headers.json
                └── body.json           

Split cache by request URL params

To split cache by request query params, you can set extraDir to a function. It accepts request as a first argument and gives access to any prop of the request:

test('test', async ({ page, cacheRoute }) => {
  await cacheRoute.GET('/api/cats*', {
    extraDir: req => new URL(req.url()).searchParams.toString()
  });
  // ...
});

Notice * in /api/cats* to match query params

Given the following requests:

GET /api/cats?foo=1
GET /api/cats?foo=2

Cache structure will be:

.network-cache
└── example.com
    └── api-cats
        └── GET
            ├── foo=1
            │   ├── headers.json
            │   └── body.json
            └── foo=2
                ├── headers.json
                └── body.json

Split cache by request body

To split cache by request body, you can set extraDir to a function. It accepts request as a first argument and gives access to any prop of the request:

test('test', async ({ page, cacheRoute }) => {
  await cacheRoute.GET('/api/cats', {
    extraDir: req => req.postDataJSON().email
  });
  // ...
});

Having the following requests:

POST -d '{"email":"user1@example.com"}' /api/cats
POST -d '{"email":"user2@example.com"}' /api/cats

Cache structure will be:

.network-cache
└── example.com
    └── api-cats
        └── POST
            ├── user1@example.com
            │   ├── headers.json
            │   └── body.json
            └── user2@example.com
                ├── headers.json
                └── body.json

Change base dir

By default, cache files are stored in .network-cache base directory. To change this location, set baseDir option:

export const test = base.extend<{ cacheRoute: CacheRoute }>({
  cacheRoute: async ({ page }, use, testInfo) => {
    await use(new CacheRoute(page, {
      baseDir: `test/.network-cache`
    }));
  }
});

Moreover, you can set separate baseDir for each Playwright project or each test:

export const test = base.extend<{ cacheRoute: CacheRoute }>({
  cacheRoute: async ({ page }, use, testInfo) => {
    await use(new CacheRoute(page, {
      baseDir: `test/.network-cache/${testInfo.project.name}`
    }));
  }
});

Example of generated structure

.network-cache
├── project-one
│   └── example.com
│       └── api-cats
│           └── GET
│               ├── headers.json
│               └── body.json
└── project-two
    └── example.com
        └── api-cats
            └── GET
                ├── headers.json
                └── body.json

In that example, you get more isolation, but less cache re-use. It's a trade-off, as always 🤷‍♂️

Multi-step cache in complex scenarios

For complex scenarios, you may want to have different cached responses for the same API. Example: adding a new todo item into the todo list.

With caching in mind, the plan for such test can be the following:

1. Set cache for GET request to load original todo items
2. Open the todo items page
3. Set cache for POST request to create new todo item
4. Set cache for GET request to load updated todo items
5. Enter todo text and click "Add" button
6. Assert todo list is updated

The implementation utilizes extraDir option to dynamically change cache path in the test:

test('adding todo', async ({ page, cacheRoute }) => {
  // set cache for GET request to load todo items
  await cacheRoute.GET('/api/todo');

  // ...load page

  // CHECKPOINT: change cache dir, all subsequent requests will be cached in `after-add` dir
  cacheRoute.options.extraDir.push('after-add');

  // set cache for POST request to create a todo item
  await cacheRoute.POST('/api/todo');
  
  // ...add todo item
  // ...reload page
  // ...assert todo list is updated
});

Generated cache structure:

.network-cache
└── example.com
    └── api-todo
        ├── GET
        │   ├── headers.json
        │   ├── body.json
        │   └── after-add
        │       ├── headers.json
        │       └── body.json
        └── POST
            └── after-add
                ├── headers.json
                └── body.json

You may still modify cached responses to match test expectation. But it's better to make it as replacement modifications, not changing the structure of the response body. Keeping response structure unchanged is more "end-2-end" approach.

API

The CacheRoute class manages caching of routes for a Playwright Page or BrowserContext. It simplifies setting up HTTP method handlers for specific routes with caching options.

Constructor

const cacheRoute = new CacheRoute(page, options?)

• page: The Playwright Page or BrowserContext to manage routes.
• options: Optional configuration to control caching behavior.

Methods

These methods enable caching for specific HTTP routes:

• cacheRoute.GET(url, optionsOrFn?)
• cacheRoute.POST(url, optionsOrFn?)
• cacheRoute.PUT(url, optionsOrFn?)
• cacheRoute.PATCH(url, optionsOrFn?)
• cacheRoute.DELETE(url, optionsOrFn?)
• cacheRoute.HEAD(url, optionsOrFn?)
• cacheRoute.ALL(url, optionsOrFn?)

Params

• url: Url pattern
• optionsOrFn: Caching options or a function to modify the response

Options

You can provide options to CacheRoute constructor or modify them dynamically via cacheRoute.options. All values are optional.

baseDir

string

Base directory for cache files.

extraDir

string | string[] | ((req: Request) => string | string[])

Additional directory for cache files. Can be a string, array of strings, or a function that accepts a request and returns a string or an array of strings.

match

(req: Request) => boolean

Function to add additional matching logic for requests. Returns true to cache, or false to skip.

httpStatus

number

Cache responses with the specified HTTP status code.

ttlMinutes

number

Time to live for cached responses, in minutes.

overrides

RequestOverrides | ((req: Request) => RequestOverrides)

Object or function that provides request overrides (e.g., headers, body) when making real calls.

modify

(route: Route, response: APIResponse) => Promise<unknown>

Function to modify the response before caching. This is called for each route.

modifyJSON

(json: any) => any

Helper function to modify JSON responses before caching.

noCache

boolean

If true, disables caching and always makes requests to the server.

forceUpdate

boolean

If true, always requests from the server and updates the cached files.

buildCacheDir

(ctx: BuildCacheDirArg) => string[]

Function to build a custom cache directory, providing fine-grained control over the cache file location. Default implementation.

Debug

To debug caching, run Playwright with the following DEBUG environment variable:

DEBUG=playwright-network-cache npx playwright test

Motivation

Playwright has built-in support for HAR format to record and replay network requests. But when you need more fine-grained control of network, it becomes messy. Check out these issues where people struggle with HAR:

• #21405
• #30754
• #29190

This library intentionally does not use HAR. Instead, it generates file-based cache structure, giving you full control of what and how is cached.

Alternatives

Alternatively, you can check the following packages:

• playwright-intercept - uses Cypress-influenced API
• playwright-advanced-har - uses HAR format
• playwright-request-mocker uses HAR format, looks abandoned

Changelog

0.2.1

• handle requests after page is closed

0.2.0

• new api released (breaking)

Feedback

Feel free to share your feedback and suggestions in issues.

License

MIT