HTTP Mocker

HTTP Mocker can be used to simulate HTTP responses from an API service. It returns a response that is identical to the payload of the request. It can also be helpful in mocking AJAX requests made by third party Javascript libraries.

Usage

The release page currently has a pre-built binary for Ubuntu x64. If there is enough demand, additional pre-built binary may be added in the future. For now, you have to manually build the binary for other platforms.

To build HTTP Mocker, you need Go installed. Once you have Go installed, clone this repository and build it:

git clone https://github.com/kulshekhar/http-mocker
cd http-mocker
go build

To run it:

./http-mocker

Note: This starts HTTP Mocker on port 18000. You can customize the port by setting the INTERCEPTOR_PORT environment variable.

Now HTTP Mocker will respond to an HTTP POST request with a response identical to the value of the response key from the request payload. For example, if you make the following request:

curl -X POST -H 'Content-Type:application/json' -d '{"response":1}' -i http://localhost:18000

HTTP Mocker will respond with 1. If you make the following request:

curl -X POST -H 'Content-Type:application/json' -d '{"response":{"f1":"aa"}}' -i http://localhost:18000

HTTP Mocker will respond with:

{"f1":"aa"}

AJAX Interceptor

When HTTP Mocker is running, accessing http://localhost:18000/_script.js will serve a script that will allow you to intercept and redirect AJAX requests. You can include it like so:

<script src="http://localhost:18000/_script.js"></script>

and use it in this manner:

let xi = new XHRInterceptor();

xi.matchAll([
  { expression: /\/post\/[0-9]+\/[a-zA-Z]+/, response: { message: 'nice post' }, statusCode: 200 },
  { expression: '/get', response: { message: 'nice get' } },
]);

xi.intercept();

The above snippet will intercept two types of AJAX requests (to any domain):

• all POST requests to any URL whose pathname match the form /post/<SOME_NUMBER>/<SOME_TEXT> (for example, http://example.com/post/123/abc)
• all GET requests to /get

You can also set the statusCode for a particular matcher. If set, HTTP Mocker will respond with this status code. The default response status code is 200.

these requests will be replaced by POST requests to HTTP Mocker. The content of the response key in the matcher will be the payload sent to HTTP Mocker.

For example, the equivalent curl command for the first matcher will be:

curl -X POST -H 'Content-Type:application/json' -d '{"response":{"message":"nice post"}}' -i http://localhost:18000

and the equivalent curl command for the second matcher will be:

curl -X POST -H 'Content-Type:application/json' -d '{"response":{"message":"nice get"}}' -i http://localhost:18000

To be effective, the value of the response key should be identical to the actual response of the API call that is being mocked.