'Fake' an API response for testing - php

Question

We are trying to recreate some of the responses from a live API locally for testing purposes.
We are trying to build a very basic PHP replica that responds to the Ajax requests with JSON.The code below is what I have it returning right now as a string and the error on the other end throws up an error:
"Uncaught TypeError: Cannot read property 'instanceId' of undefined".
code:
$var = "{'request':{'instanceId':'1234546','usage':'1'}}";
echo($var);
We have tested and it works with the live API. So it something that I am doing wrong when trying to return the dummy JSON data. Now as far as I am aware this is not a valid JSON response, is there a way to easily 'fake' the response with something like I have above?

Answer 1

That isn't valid json. Reverse your quotes. Single on the outside, double on the inside.
You may also need to return a correct content-type header.
$var = '{"request":{"instanceId":"1234546","usage":"1"}}';
header("Content-Type", "application/json");
echo($var);
Or better yet:
$obj = array("request" => array("instanceId" => "123456", "usage" => "1"));
header("Content-Type", "application/json");
echo(json_encode($obj));

Answer 2

To keep your tests local you can use Jaqen, a very light server built for testing scripts that depend of an API.
You set whatever you want it to respond directly on the request.
For example:
# Console request to a Jaqen instance listening at localhost:9000
$ curl 'http://localhost:9000/echo.json?request\[instanceId\]=123456&request\[usage\]=1' -i
=> HTTP/1.1 200 OK
=> Content-Type: application/json
...
=> {"request":{"instanceId":"1234546","usage":"1"}}
There are several ways to tell it what to do and also serves static files to allow loading test pages and assets, check out the documentation for more.
It's built on node.js so it's really easy to install and use it locally.
# To install it (once you have node.js):
$ npm install -g jaqen
# To run it just type 'jaqen' on the console:
$ jaqen
=> Jaqen v1.0.0 is listening on port 9000.
=> Press Ctl+C to stop the server.
That's it!