yaktime

Record HTTP interactions The Node Way™. Inspired by ruby's vcr.

This is a complete rewrite of original project yakbak in Typescript.

All existing tapes works with this implementation

install

$ npm install yaktime --save-dev
$ yarn add --dev yaktime

usage

The main idea behind testing HTTP clients with yaktime is:

Make your client's target host configurable.
Set up a yaktime server locally to proxy the target host.
Point your client at the yaktime server.

Then develop or run your tests. If a recorded HTTP request is found on disk, it will be played back instead of hitting the target host. If no recorded request is found, the request will be forwarded to the target host and recorded to disk.

yaktime(host, options)

Returns a function of the signature function (req, res) that you can give to an http.Server as its handler.

const handler = yaktime("http://api.flickr.com", {
  dirname: __dirname + "/tapes"
});

options

dirname the path where recorded responses will be written (required).
noRecord if true, requests will return a 404 error if the tape doesn't exist
recordOnlySuccess if true, only successful requests (response status code = 2XX) will be recorded
hash(req, body) provide your own IncomingMessage hash function

with node's http module

yaktime provides a handler with the same signature that http.Server expects so you can create your own proxy:

const http = require("http");
const { yaktime } = require("yaktime");

http
  .createServer(
    yaktime("http://api.flickr.com", {
      dirname: __dirname + "/tapes"
    })
  )
  .listen(3000);

Now any requests to http://localhost:3000 will be proxied to http://api.flickr.com and recorded to /tapes for future playback.

with express

Need more flexibility? express expects the same function signature, so you can use yaktime just like you would any other middleware:

const express = require("express");
const { yaktime } = require("yaktime");

const flickr = yaktime("http://api.flickr.com", {
  dirname: __dirname + "/tapes"
});

const upload = yaktime("http://up.flickr.com", {
  recordOnlySuccess: true,
  dirname: __dirname + "/tapes"
});

const app = express();

app.use(function(req, res, next) {
  if (req.path.indexOf("/services/upload") === 0) {
    upload(req, res);
  } else {
    flickr(req, res);
  }
});

function logErrors(err, req, res, next) {
  console.error(err.stack);
  next(err);
}
app.use(logErrors);
function clientErrorHandler(err, req, res, next) {
  if (req.xhr) {
    res.status(500).send({ error: "Something failed!" });
  } else {
    next(err);
  }
}
app.use(clientErrorHandler);
function errorHandler(err, req, res, next) {
  res.status(500);
  res.render("error", { error: err });
}
app.use(errorHandler);

app.listen(3000);

as a standalone response server

Each recorded response is itself a node module with the same handler signature, so if you want to create a server that replays a single response, you can do so easily:

const http = require("http");
const tape = require("./tapes/1117f3d81490d441d826dd2fb26470f9.js");

http.createServer(tape).listen(3000);

on the command line

yaktime also ships with a yaktime utility that will start an HTTP server to play back a given tape.

$ yaktime
Error: file is required
Usage: yaktime <file>
$ yaktime ./tapes/1117f3d81490d441d826dd2fb26470f9.js
Server listening on port 3000
* Connection from 127.0.0.1 port 63669
< GET / HTTP/1.1
< host: localhost:3000
< user-agent: curl/7.43.0
< accept: */*
<
> HTTP/1.1 201 Created
> content-type: text/html
> date: Sat, 26 Oct 1985 08:20:00 GMT
> connection: close
> transfer-encoding: chunked
>
* Connection closed

why not [insert other project here]?

Check out this blog post about why we chose a reverse proxy over other existing approaches to recording HTTP interactions.

license

This software is free to use under the MIT license. See the LICENSE file for license text and copyright information.

yknx4/yaktime