Moxy

She’s alive. And, her name is Moxy.

Simply put, Moxy is an HTTP proxy that acts like a regular HTTP proxy, but it also allows you to mock responses, including support for delays and conditional statements.

Why is this useful? Consider the following use case…

You’re working on a team of two. You’re responsible for the client code and the other handles the server side. Let’s call the other, Backend Billy. Backend Billy is great most of time. However, lately, he’s been a little distracted, affecting his ability to deliver on the RESTful API that you need to get on with your client side work. Of course, being a good team, you spec out the API beforehand and have an interface to work against. You’ve got a bunch of code written up, but you can’t test real, live network requests because the API service doesn’t exist yet. Moxy can help here.

Let’s say you’ve spec’d out three endpoints…

http://api.awesomeapp.com/v1/awesome http://api.awesomeapp.com/v1/awesome/add http://api.awesomeapp.com/v1/awesome/:id

Using Moxy, you can add the following configuration entries into moxy.conf…

url http://api.awesomeapp.com/v1/awesome/?$
  get 200 awesome.json

url http://api.awesomeapp.com/v1/awesome/add
  get 400 awesome_add_error.json
  post 200 awesome_add.json

url http://api.awesomeapp.com/v1/awesome/?\?id\=.+
  get 400 awesome_id_error.json
  if created: get 200 awesome_id.json

Now, with Moxy up and running and your system configured to use her as an HTTP proxy, you can happily test your client code as if the backend is fully implemented, even though Backend Billy is still dilly dallying.

Notice the line that reads if created: get 200 awesome_thing.html. It’s a conditional statement with a condition called created. This allows the success response to be delayed until necessary. You can see and manipulate all conditions by browsing http://localhost:9889/config/conditions.

Additionally, let’s say you’ve added some nifty error handling logic when the add request takes longer than 10 seconds. To test, you can modify moxy.conf as follows…

url http://api.awesomeapp.com/v1/awesome/add
  if delay: delay 13000
  get 400 awesome_add_error.json
  post 200 awesome_add.json

This tells Moxy to delay the response for 13 seconds if the delay condition evaluates to true.

And, if none of that interests you and you just want Billy to get back to work, you could sneak on to his computer and configure Moxy with something like…

url ^.+\.facebook\.com
  get 301
  header Location http://awesomeapp.com/api/documentation

Moxy is written in Python, open source, and available on Github.