`messageBody` mangles json-ish inputs

[aviv-amdocs]

I'm trying to use Spring Cloud Contract to test Messaging (Spring Cloud Stream over Kafka).
The message I need to send is JSON encoded, and one of its fields is a JSON encoded string, like this:

    {
        "type": "x",
        "payload": "{\"a\": 4}"
    }

Using Spring Cloud Contract Maven Plugin, versions 2.2.6.RELEASE or 3.0.1.

This is the contract file - node body is provided as a String:

import org.springframework.cloud.contract.spec.Contract

Contract.make{
	input {
		messageBody('   {"type": "x","payload": "{\\"a\\": 4}"}')
	}
}

and this is the generated test class (trimmed for focus):

public class Sunny_dayTest extends AsyncBaseClass {
	@Inject ContractVerifierMessaging contractVerifierMessaging;
	@Inject ContractVerifierObjectMapper contractVerifierObjectMapper;

	@Test
	public void validate_notifyChangeUpdate() throws Exception {
		// given:
			ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
					"{\"type\":\"x\",\"payload\":{\"a\":4}}"
						, headers()
			);

		// when:;
		}
	}

The message in the Java file is altered from my input; Here it is printed and formatted:

{
  "type": "x",
  "payload": {
    "a": 4
  }
}

(Note that value of payload is now an object, not a string!)

It appears that the value of messageBody is being recursively parsed and reassembled.

Some other values are also modified:

messageBody(' [][]]') becomes "[]" (leading whitespace removed, as well as all content that can't be parsed as json).
And, hilariously, messageBody(file('message.json')) translates into ...create("new String(fileToBytes(this, \"notifyChangeUpdate_request_message.json\")), ...)"

Is there a way to provide an arbitrary string to messageBody and have it used as the message?

[marcingrzejszczak]

I see the problem... maybe try sending it as bytes?

[aviv-amdocs]

messageBody('{"type": "x"}'.getBytes())

generates:

ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
		"[123,34,116,121,112,101,34,58,32,34,120,34,125]"
			, headers()

...which is also not exactly right for me.

[marcingrzejszczak]

no no, fileAsBytes() not .getBytes()

[aviv-amdocs]

Ah, yeah, filesAsBytes() seems to actually work:

messageBody(fileAsBytes('message.json') )

-->

contractVerifierMessaging.create(
		fileToBytes(this, "notifyChangeUpdate_withbug_request_message.json")
	, headers()

thanks :)

[marcingrzejszczak]

Cool, can we close this? :)

[aviv-amdocs]

Are you OK with this behavior? especially the one with file()?

[marcingrzejszczak]

The problem is that you have a JSON in a JSON. This is why we're parsing the JSON as JSON and your JSON in payload is also parsed. It's hard to fix really 😬 So I think that if you have the case where you don't want this to be parsed as we do then you should use the approach with fileAsBytes(...).

[aviv-amdocs]

Why would you parse JSON at all?

This can also show up in other strange places:

 {
        "methodName": "numbers",
        "returnValue": "[]int"
    }

will remove int from the returnValue types ([]int is a type in Go-lang).

If the input is a String, why bother manipulating it?

[marcingrzejszczak]

Maybe it's a bug then - I can't do the investigation right now 😬

[marcingrzejszczak]

Is this also a problem in version 4.0.x of Spring Cloud Contract? We've changed the messaging contracts to only include the triggeredBy and outputMessage parts.