Add ability to map Custom DSL to stub generation

[jamietanna]

Is your feature request related to a problem? Please describe.

When using the Custom DSL, such as:

BaseTestClass

```java package uk.gov.api.springboot.contract; import io.restassured.module.mockmvc.RestAssuredMockMvc; import java.util.UUID; import org.junit.jupiter.api.BeforeEach; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.test.annotation.DirtiesContext; import org.springframework.web.context.WebApplicationContext; @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.MOCK) @DirtiesContext public class BaseTestClass { @Autowired WebApplicationContext context; @BeforeEach void setup() { RestAssuredMockMvc.webAppContextSetup(context); } public String correlationId() { return UUID.randomUUID().toString(); } } ```

A contract such as:

canGet.groovy

```groovy package contracts.example import org.springframework.cloud.contract.spec.Contract Contract.make { request { method 'GET' url '/apis' headers { accept('application/*+json') header('correlation-id', execute('correlationId()')) } } response { status OK() headers { contentType('application/vnd.uk.gov.api.v1alpha+json') } } } ```

Gets created as the following:

canGet.json

```json { "id" : "32eb1ebb-32d6-463a-a660-b898f5102cc7", "request" : { "url" : "/apis", "method" : "GET", "headers" : { "Accept" : { "matches" : "application/\\*\\+json.*" }, "correlation-id" : { "equalTo" : "correlationId()" } } }, "response" : { "status" : 200, "headers" : { "Content-Type" : "application/vnd.uk.gov.api.v1alpha+json" }, "transformers" : [ "response-template", "spring-cloud-contract" ] }, "uuid" : "32eb1ebb-32d6-463a-a660-b898f5102cc7" } ```

However, there is no definition available to Wiremock for what correlationId() provides, so will fail, which reduces the utility of extending the DSL.

Describe the solution you'd like

Either:

• Provide a means for autogenerated transformer(s) in Wiremock to produce the custom functions
• Provide an extension point for users to provide the logic

Describe alternatives you've considered

N/A

Additional context

N/A

[marcingrzejszczak]

Why not call

      header('correlation-id', $(p(execute('correlationId()')), c("abcdefgh")))

so for the producer side you call a method and for the consumer you're explicit about the value?

[jamietanna]

That's a good shout - that would solve this problem :+1:

A slightly more complex example I'd want to use is where we're producing an ID Token or a JWT-based Access Token, which for the purpose of our tests would need to be in a specific format, possibly with some claims, and most importantly, signed for the server it's executing against.

It's unlikely that the consumer's integrated service works with the same signing key that the local test version does, so we'd want it dynamic.

See also the use of a client_secret or other authentication/authorization means that wouldn't be ideal to track in source control

[marcingrzejszczak]

I wouldn't expect that secret or token to be one from production. That would have to be a test version that would be used instead of a real one in your tests.

[jamietanna]

Interesting, thanks. This looks similar to what Pact recommends so looks like the way that most folks would assume to have this done :+1:

I think this issue can be closed - is there anything else we want to add to track / better document the syntax you mentioned above so folks don't have stubs that will never match correctly?

[marcingrzejszczak]

I think that's all (we describe the producer(...) and consumer(...) methods in the docs https://docs.spring.io/spring-cloud-contract/docs/3.1.0/reference/html/project-features.html#contract-dsl-dynamic-properties-in-body ). Thanks for reporting the issue :)