stojanovic / fake-http-request

Fake Node.js HTTP/HTTPS request interface that makes it easy to write unit tests that capture/mock outgoing network requests

Fake Node.js HTTP Request

Utility class to fake a HTTP/HTTPS request for unit testing Node.js projects. It captures arguments for outgoing requests and allows you to simulate network errors and responses easily. It can also pipe outgoing HTTP/S requests to custom functions, so you can asynchronously wait for them.

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Installation

Install using NPM, with

npm install fake-http-request -D

Usage

Before the relevant HTTP/S requests, install the fake request:

var fake = require('fake-http-request');

fake.install('https');

To clean up and restore the original HTTP/S requests, after testing, use:

fake.uninstall('https');

This will replace the system https.request with a test method that captures calls instead of sending them out to the network, so it will work with any client code that uses the system http/https libraries.

Both install and uninstall can take an argument -- the module name where to install the fake requests. By default, they will use https.

You can then use https.request.calls to inspect individual calls. Each call object will have the following structure:

• args: array -- arguments passed to the request
• body: array -- chunks written to the request body
• networkError: function (error) -- use this to simulate a network error for the call.
• respond: function(httpCode, statusMessage, body) -- use this to simulate a successful network response.

You can also use https.request.pipe to pass in a function that will receive a call every time a network request is initiated. The call is executed using setTimeout so you can also respond, knowing that the synchronous processing of the calling function is complete. The arguments to the pipe will be the arguments passed to the HTTP call, and this will be set to the fake request.

Example

var fakeRequest = require('fake-http-request'),
    https = require('https'),
    request = require('request');

fakeRequest.install();

// simulate a response

request('https://www.google.com', function (error, response, body) { 
  console.log('got response', response.statusCode, response.statusMessage, body) 
}).on('request', function () {
  console.log('number of calls', https.request.calls.length);
  console.log('first call', 
	https.request.calls[0].args[0].host, 
	https.request.calls[0].args[0].port, 
	https.request.calls[0].args[0].path
  );

  https.request.calls[0].respond(404, 'Not found', 'some html here');
});

// simulate errors

call = request('https://www.google.com', function (error, response, body) { 
  console.log('got error', error); 
}).on('request', function () {
  var mostRecent = https.request.calls.length - 1;
  console.log('number of calls', https.request.calls.length);
  console.log('second call', 
    https.request.calls[mostRecent].args[0].host,
	https.request.calls[mostRecent].args[0].port, 
	https.request.calls[mostRecent].args[0].path
  );
  https.request.calls[mostRecent].networkError('BOOM!');
});

// pipe calls for async processing

https.request.pipe(function (options) {
  console.log('Received call', options); 
  this.respond(200, 'OK', 'some html here');
});

request('https://www.google.com');