xhr-mocklet

XMLHttpRequest mocking

Utility for mocking XMLHttpRequests both in the browser and nodejs. It's primary use case is for unit tests, allowing you to respond with mock responses, trigger timeouts, etc.

This library comes with complete TypeScript declaration files.

Installation

# NPM
npm install --save --dev xhr-mocklet

# Or via yarn:
yarn add --dev xhr-mocklet

Usage

const mock = require('xhr-mocklet');

// Replace the real XHR object with the mock XHR object
mock.setup();

// Mock a response for all POST requests to http://localhost/api/user
mock.post('http://localhost/api/user', (req, res) => {
  return res
    .status(201)
    .header('Content-Type', 'application/json')
    .body({
      lastName: 'John',
      firstName: 'Smith'
    });
});

// Restore the original XHR object when all your tests are done.
mock.teardown();

Simulating an error

Simply return null from your response handler:

mock.post('http://localhost/foo', (req, res) => null);

Simulate a timeout

mock.post('http://localhost/foo', (req, res) => res.timeout(true));

Use mocked XMLHttpRequest

You can even use a mocked XMLHttpReqeuest instance to create Requests:

// Create an instance of the (mock) XHR object and use as per normal
const xhr = new XMLHttpRequest();

xhr.onreadystatechange = () => {
  if (xhr.readyState === xhr.DONE) {
    // when you're finished put the real XHR object back
    mock.teardown();
  }
}

API

Builder

Method	Description
setup()	Replace the global XMLHttpRequest object with the MockXMLHttpRequest.
teardown()	Restore the global XMLHttpRequest object to its original state.
reset()	Remove all request handlers.
get(url: string | regex, callback)	Create GET mock response for a specific url.
post(url: string | regex, callback)	Create POST mock response for a specific url.
put(url: string | regex, callback)	Create PUT mock response for a specific url.
patch(url: string | regex, callback)	Create PATCH mock response for a specific url.
delete(url: string | regex, callback)	Create DELETE mock response for a specific url.
mock(callback)	Register mock response for every request.

MockXMLHttpRequest

The api is practically similar to the native XMLHttpRequest.

MockRequest

Method	Description
method(): string	Get the request method.
url(): string	Get the request URL.
query(): object	Get the parsed query part of the request URL.
header(name: string): string	Get a request header.
headers(): object	Get all request headers.
body(): string	Get the request body.

MockResponse

Method	Description
status(): number	Get the response status.
status(code: number)	Set the response status.
header(name: string): string	Get a response header.
header(name: string, value: string)	Set a response header.
headers(): object	Get response headers.
headers(headers: obejct)	Set response headers.
body(): string	Get response body.
body(body: string)	Set response body.
timeout(): boolean | number	Get weather the response will trigger a timeout.
timeout(ms: boolean | number)	Set a timeout, otherwise default to the value set on the XHR object.
progress(loaded: number, total: number, lengthComputable: boolean)	Trigger progress event. Pass in loaded size, total size and if event is lengthComputable.

Special Thanks

Special thanks goes to James Newell for his xhr-mock library. xhr-mocklet started out as a fork of his work.