WireMock Async Transformer

Make asynchronous request after the response. When just the response simply not enough.

Intro

The reason why the extension exists: sometimes you need to perform async request after the response, e.g. to invoke remote webhook.

Typically, it's not required during the automated tests. But if you want to mock something on the pre-production system very "quick and dirty", the solution might be helpful.

So you don't have to "hold" some additional runtime, async request "from the box" doing what you want.

This transformer creates separated thread, which waiting for the given interval of time and then performs a HTTP request.

      initiator
    ┌─────────────┐  requests mock     ┌────────────┐
    │             │ ─(1)─────────────> │            │
    │  Service 1  │                    │  WireMock  │
    │             │ <────────────(2)── │            │
    └─────────────┘  mocked response   └────────────┘
                                             │
                                   [after n sec. delay]
                                             │
    ┌─────────────┐                         (3)  <┈┈┈┈ here the magic happens
    │             │                          │
    │  Service 2  │ <════════════════════════╛
    │             │  async request from wm
    └─────────────┘
      waits for a
      request

e.g. delay = 5 sec., then the request (3) will be performed after the 5 seconds after response (2)

Adding to the WireMock

There is many possible ways to add the extension to your WireMock server, e.g.:

• This article explains everything, or...
• ...How to add an extension to the docker container

Arguments and transformer name

Transformer name: async-request, use this name in "transformers" json section of the mapping

Argument Key	Type	Description (Request)	Required
url	String	URL, starting from "http://", incl. full path	True
body	String	String representation of the async request body	False
method	String	HTTP method: GET, POST, PUT, DELETE, PATCH, etc.	True
delay	Integer	Wait for the given amount of milliseconds before the request	False, default 5s
headers	Object	Headers represented by the json object as a pairs of a key-values	False

Example json mapping with the extension enabled

In this example we're going to use the WireMock itself in order to catch the async request

• Create new mapping with the following json (change localhost if you have different hostname/ip):

{
    "request": { 
        "urlPattern": "^/example/async/initiate.*$",
        "method": "ANY"
    },
    "response": {
        "status": 200,
        "headers": {
            "Content-Type": "application/json"
        },
        "body": "{\"status\": \"This is usual sync response\"}",
        "transformers": [
            "async-request"
        ],
        "transformerParameters": {
            "method": "POST",
            "url": "http://localhost/example/async/request",
            "body": "This is my async-request plugin request",
            "headers": {
                "X-Async-Request": true,
                "Content-Type": "text/plain"
            },
            "delay": 5000
        }
    }
}

• Send any request to the WireMock endpoint: example/async/initiate
• Wait for a 5 seconds
• Check your GET /__admin/requests log, you should find two requests (second is made by async-request)