light-my-request

What is light-my-request?

The light-my-request npm package is a lightweight HTTP request simulation tool designed primarily for testing purposes. It allows developers to simulate HTTP requests to their Node.js applications without the need for a real server. This is particularly useful for testing route handlers and middleware in isolation.

What are light-my-request's main functionalities?

Simulate HTTP GET Request

This feature allows you to simulate an HTTP GET request to a given handler function. The response can then be inspected to verify the behavior of the handler.

const { inject } = require('light-my-request');
const handler = (req, res) => { res.end('Hello, world!'); };

inject(handler, { method: 'GET', url: '/' }, (err, res) => {
  console.log(res.payload); // 'Hello, world!'
});

Simulate HTTP POST Request with Payload

This feature allows you to simulate an HTTP POST request with a payload. The handler can process the payload, and the response can be inspected to verify the behavior.

const { inject } = require('light-my-request');
const handler = (req, res) => {
  let body = '';
  req.on('data', chunk => { body += chunk; });
  req.on('end', () => { res.end(`Received: ${body}`); });
};

inject(handler, { method: 'POST', url: '/', payload: 'Hello, world!' }, (err, res) => {
  console.log(res.payload); // 'Received: Hello, world!'
});

Simulate HTTP Request with Headers

This feature allows you to simulate an HTTP request with custom headers. The handler can access these headers, and the response can be inspected to verify the behavior.

const { inject } = require('light-my-request');
const handler = (req, res) => {
  res.end(`Header: ${req.headers['x-custom-header']}`);
};

inject(handler, { method: 'GET', url: '/', headers: { 'x-custom-header': 'test-value' } }, (err, res) => {
  console.log(res.payload); // 'Header: test-value'
});

Other packages similar to light-my-request

supertest

Supertest is a popular HTTP assertion library that works with any test framework. It allows you to test HTTP endpoints by making requests and asserting on the responses. Compared to light-my-request, Supertest is more feature-rich and integrates well with various testing frameworks like Mocha and Jest.

nock

Nock is an HTTP mocking and expectations library for Node.js. It allows you to intercept HTTP requests and provide predefined responses, making it useful for testing HTTP clients. Unlike light-my-request, which focuses on simulating requests to handlers, Nock is more about mocking external HTTP requests.

axios-mock-adapter

Axios-mock-adapter is a library that allows you to mock requests made using the Axios HTTP client. It provides a way to define how requests should be handled and what responses should be returned. This is different from light-my-request, which is more focused on simulating requests to server handlers rather than mocking client-side requests.

README

Light my Request

Injects a fake HTTP request/response into a node HTTP server for simulating server logic, writing tests, or debugging. Does not use a socket connection so can be run against an inactive server (server not in listen mode).

Example

const http = require('node:http')
const inject = require('light-my-request')

const dispatch = function (req, res) {
  const reply = 'Hello World'
  res.writeHead(200, { 'Content-Type': 'text/plain', 'Content-Length': reply.length })
  res.end(reply)
}

const server = http.createServer(dispatch)

inject(dispatch, { method: 'get', url: '/' }, (err, res) => {
  console.log(res.payload)
})

Note how server.listen is never called.

Async await and promises are supported as well!

// promises
inject(dispatch, { method: 'get', url: '/' })
  .then(res => console.log(res.payload))
  .catch(console.log)

// async-await
try {
  const res = await inject(dispatch, { method: 'get', url: '/' })
  console.log(res.payload)
} catch (err) {
  console.log(err)
}

You can also use chaining methods if you do not pass the callback function. Check here for details.

// chaining methods
inject(dispatch)
  .get('/')                   // set the request method to GET, and request URL to '/'
  .headers({ foo: 'bar' })    // set the request headers
  .query({ foo: 'bar' })      // set the query parameters
  .end((err, res) => {
    console.log(res.payload)
  })

inject(dispatch)
  .post('/')                  // set the request method to POST, and request URL to '/'
  .payload('request payload') // set the request payload
  .body('request body')       // alias for payload
  .end((err, res) => {
    console.log(res.payload)
  })

// async-await is also supported
try {
  const chain = inject(dispatch).get('/')
  const res = await chain.end()
  console.log(res.payload)
} catch (err) {
  console.log(err)
}

File uploads (multipart/form-data) or form submit (x-www-form-urlencoded) can be achieved by using form-auto-content package as shown below:

const formAutoContent = require('form-auto-content')
const fs = require('node:fs')

try {
  const form = formAutoContent({
    myField: 'hello',
    myFile: fs.createReadStream(`./path/to/file`)
  })

  const res = await inject(dispatch, {
    method: 'post',
    url: '/upload',
    ...form
  })
  console.log(res.payload)
} catch (err) {
  console.log(err)
}

This module ships with a handwritten TypeScript declaration file for TS support. The declaration exports a single namespace LightMyRequest. You can import it one of two ways:

import * as LightMyRequest from 'light-my-request'

const dispatch: LightMyRequest.DispatchFunc = function (req, res) {
  const reply = 'Hello World'
  res.writeHead(200, { 'Content-Type': 'text/plain', 'Content-Length': reply.length })
  res.end(reply)
}

LightMyRequest.inject(dispatch, { method: 'get', url: '/' }, (err, res) => {
  console.log(res.payload)
})

// or
import { inject, DispatchFunc } from 'light-my-request'

const dispatch: DispatchFunc = function (req, res) {
  const reply = 'Hello World'
  res.writeHead(200, { 'Content-Type': 'text/plain', 'Content-Length': reply.length })
  res.end(reply)
}

inject(dispatch, { method: 'get', url: '/' }, (err, res) => {
  console.log(res.payload)
})

The declaration file exports types for the following parts of the API:

• inject - standard light-my-request inject method
• DispatchFunc - the fake HTTP dispatch function
• InjectPayload - a union type for valid payload types
• isInjection - standard light-my-request isInjection method
• InjectOptions - options object for inject method
• Request - custom light-my-request request object interface. Extends Node.js stream.Readable type by default. This behavior can be changed by setting the Request option in the inject method's options
• Response - custom light-my-request response object interface. Extends Node.js http.ServerResponse type

API

inject(dispatchFunc[, options, callback])

Injects a fake request into an HTTP server.

• dispatchFunc - listener function. The same as you would pass to Http.createServer when making a node HTTP server. Has the signature function (req, res) where:
  • req - a simulated request object. Inherits from Stream.Readable by default. Optionally inherits from another class, set in options.Request
  • res - a simulated response object. Inherits from node's Http.ServerResponse.
• options - request options object where:
  • url | path - a string specifying the request URL.
  • method - a string specifying the HTTP request method, defaulting to 'GET'.
  • authority - a string specifying the HTTP HOST header value to be used if no header is provided, and the url does not include an authority component. Defaults to 'localhost'.
  • headers - an optional object containing request headers.
  • cookies - an optional object containing key-value pairs that will be encoded and added to cookie header. If the header is already set, the data will be appended.
  • remoteAddress - an optional string specifying the client remote address. Defaults to '127.0.0.1'.
  • payload - an optional request payload. Can be a string, Buffer, Stream or object. If the payload is string, Buffer or Stream is used as is as the request payload. Oherwise it is serialized with JSON.stringify forcing the request to have the Content-type equal to application/json
  • query - an optional object or string containing query parameters.
  • body - alias for payload.
  • simulate - an object containing flags to simulate various conditions:
    • end - indicates whether the request will fire an end event. Defaults to undefined, meaning an end event will fire.
    • split - indicates whether the request payload will be split into chunks. Defaults to undefined, meaning payload will not be chunked.
    • error - whether the request will emit an error event. Defaults to undefined, meaning no error event will be emitted. If set to true, the emitted error will have a message of 'Simulated'.
    • close - whether the request will emit a close event. Defaults to undefined, meaning no close event will be emitted.
  • validate - Optional flag to validate this options object. Defaults to true.
  • server - Optional http server. It is used for binding the dispatchFunc.
  • autoStart - Automatically start the request as soon as the method is called. It is only valid when not passing a callback. Defaults to true.
  • signal - An AbortSignal that may be used to abort an ongoing request. Requires Node v16+.
  • Request - Optional type from which the request object should inherit instead of stream.Readable
• callback - the callback function using the signature function (err, res) where:
  • err - error object
  • res - a response object where:
    • raw - an object containing the raw request and response objects where:
      • req - the simulated request object.
      • res - the simulated response object.
    • headers - an object containing the response headers.
    • statusCode - the HTTP status code.
    • statusMessage - the HTTP status message.
    • payload - the payload as a UTF-8 encoded string.
    • body - alias for payload.
    • rawPayload - the raw payload as a Buffer.
    • trailers - an object containing the response trailers.
    • json - a function that parses a json response payload and returns an object.
    • cookies - a getter that parses the set-cookie response header and returns an array with all the cookies and their metadata.

Notes:

• You can also pass a string in place of the options object as a shorthand for {url: string, method: 'GET'}.
• Beware when using the Request option. That might make light-my-request slower. Sample benchmark result run on an i5-8600K CPU with Request set to http.IncomingMessage:

Request x 155,018 ops/sec ±0.47% (94 runs sampled)
Custom Request x 30,373 ops/sec ±0.64% (90 runs sampled)
Request With Cookies x 125,696 ops/sec ±0.29% (96 runs sampled)
Request With Cookies n payload x 114,391 ops/sec ±0.33% (97 runs sampled)
ParseUrl x 255,790 ops/sec ±0.23% (99 runs sampled)
ParseUrl and query x 194,479 ops/sec ±0.16% (99 runs sampled)

inject.isInjection(obj)

Checks if given object obj is a light-my-request Request object.

Method chaining

There are following methods you can used as chaining:

• delete, get, head, options, patch, post, put, trace. They will set the HTTP request method and the request URL.
• body, headers, payload, query, cookies. They can be used to set the request options object.

And finally you need to call end. It has the signature function (callback). If you invoke end without a callback function, the method will return a promise, thus you can:

const chain = inject(dispatch).get('/')

try {
  const res = await chain.end()
  console.log(res.payload)
} catch (err) {
  // handle error
}

// or
chain.end()
  .then(res => {
    console.log(res.payload)
  })
  .catch(err => {
    // handle error
  })

By the way, you can also use promises without calling end!

inject(dispatch)
  .get('/')
  .then(res => {
    console.log(res.payload)
  })
  .catch(err => {
    // handle error
  })

Note: The application would not respond multiple times. If you try to invoking any method after the application has responded, the application would throw an error.

Acknowledgements

This project has been forked from hapi/shot because we wanted to support Node ≥ v4 and not only Node ≥ v8. All the credits before the commit 00a2a82 goes to the hapi/shot project contributors. Since the commit db8bced the project will be maintained by the Fastify team.

License

Licensed under BSD-3-Clause.