How define request body object property as nullable in Spring Cloud Contract Groovy DSL Contract definition?

Question

I'm working on Spring Cloud based microservices, with spring cloud contract validation of client/API between services. WireMock is used in client service side tests for services API stubbing. Spring Cloud is in version 2020.0.2 . I have following Groovy contract definition:

Contract.make {
description "Nullable sender & receiver API contract"

request {
    method POST()
    url value(consumer(regex('/message')))
    headers {
        contentType(applicationJson())
        header("x-channelId", anyNonBlankString())
    }
    body(
            sender: [
                    toEmail            : anyEmail(),
                    firstName          : anyNonBlankString(),
                    lastName           : anyNonBlankString()
            ],
            receiver: [
                    toEmail            : anyEmail(),
                    firstName          : anyNonBlankString(),
                    lastName           : anyNonBlankString()
            ]
    )
}
response {
    status CREATED()
}
}

The think I want to achieve is to have both 'sender', and 'receiver' nullable. I can define nullable (DSL optional() ) each sub-field of both, but request body can look like this:

{sender:null, receiver:null}

I've tried define multiple contracts for each possibility(one with both filled, second with sender: null , third with receiver: null , and both null). In this case, client service side WireMock, that uses above definitions for API stubbing, does not match wanted stubs to proper requests - eg when calling using request with empty sender , WireMock identifies as closest stub one with expected sender and returns 404, ignoring contract definition that expects empty sender .

Is there way to define field with internal structure as nullable? In documentation I've only saw possibility to make nullable field value, but not whole structure.

Answer 1

If a field is potentially null you should create 2 contracts. 1 with it being null and 1 with it not being null .