Hello all, I am verifying a consumer (kafka consumer handler) and a producer ( a post API call to create an object). When I create the object tvia a post request, an event is triggered and my consumer consumes a Kafka message. I have used my project (SUT) existing handler in my consumer test :

describe("receive transfer event", () => {

it("accepts a transfer", () => {

return messagePact

.given("a new transfer")

.expectsToReceive(

"Action handlers consumes a new message in Kafka topic",

) // test description is the contract identifier and should match on cosumer side

.withContent(transferBodyExpectation)

.verify(asynchronousBodyHandler(actionHandler)); //existing SUT handler function

});

});

});

Here are my questions please : 1-Is my test strategy correct/acceptable according to contract testing? 2-When running my tests I have noticed this non blocking error, I am not sure what this error means :

ERROR (29508): pact@12.4.0: no handler found for message Action handlers consumes a new message in Kafka topic

3-Finally, my provider test is failing with this message :

1.1) has a matching body

$ -> Actual map is missing the following keys: body

I am not sure why it's complaining about key body when I have set it in expected body :

const transferBodyExpectation = {

from: like("***********"),

body: {

id: like("************"),

originator: { "*************") },

beneficiary: { "*************") },

asset: like("*************"),

amountSubunits: like("*************"),

The message I am expecting from Kafka is this one : Note that I am ignoring some attributes such as to, type because they are not added by action handler map function but added by another protocol that I am not testing for now.

{

"id": "***********",

"from": "***********",

"to": [

"***********"

],

"type": "***********",

"body": {

The error seems clear to me. What is your provider sending? It looks like you haven't mapped the message producer in your verification code. What does that code look like?

Hey Matt! the mapping is based on the test description right?

Producer :

describe("a request for a new transfer", () => {

// test description is the contract identifier and should match on ion cosumer side

it("sends a valid transfer", () => {

return p.verify();

});

});

});

Yeah you haven't mapped the scenarios.

My bad, the reason was that pacts where not generated in the right folder. The mapping was fine 🙂

Ah ok, the mapping wasn't present in your code snippet above. Glad you're back on track!

Thanks, I am still a bit confused though on the final step : "verifying the provider". As explained earlier on consumer side I am using the SUT existing handler function this function consumes a message from Kafka by reading a stream. and this steps passes as expected. On the provider side though, I am creating an object through a POST request call. Once the object is created then an event is triggered then a message is added to Kafka topic then should be consumer by my consumer app. My provider test is failing on matching body check. I am wondering if this error is simply cause by my test code or my whole setup is incorrect and maybe I should not use an API call as my provider? As the response I get from a post request does not match the message to be consumed by Kafka. The message to be consumed is transformed in between.

I’m a bit confused how your provider setup is happening. Can you please share your provider verification code?

Hello Matt, here is my provider setup :

describe("Transfers provider tests", () => {
  const p = new MessageProviderPact({
    messageProviders: {
      "a request for a new transfer": providerWithMetadata(
        //should match expect to receive on consumer side
        () => createTransfer("af7625bb-b272-41c8-988a-5372d100346d"), // note this is a post REST API call
        { queue: "" },
      ),
    },
    stateHandlers: {
      "some state": () => {
        // TODO: prepare system useful in order to create a transfer
        console.log('State handler: setting up "some state" for interaction');
        return Promise.resolve(`state set to create a transfer`);
        // we can add VASP creation here
      },
    },
    logLevel: LOG_LEVEL as LogLevel,
    provider: "MyTransferProvider",
    providerVersion: versionFromGitTag(),
    //Broker validation
    pactBrokerUrl: "<https://notabene.pactflow.io/>",
    pactBrokerToken: process.env.PACT_BROKER_TOKEN || "************",
    providerVersionBranch: process.env.GIT_BRANCH || "pact-integration", // use an env var later for the brancg name
    publishVerificationResult: true,

    // Find _all_ pacts that match the current provider branch
    consumerVersionSelectors: [
      {
        matchingBranch: true,
      },
    ],
  });

  describe("send a create transfer request", () => {
    it("creates a new transfer", () => {
      return p.verify();
    });
  });
});

Thanks

() => createTransfer(“af7625bb-b272-41c8-988a-5372d100346d”), // note this is a post REST API call

so

createTransfer(…)

needs to return a JSON blob that matchers whatever is in the consumer contract. If it’s not, then that’s why it will fail

Thanks Matt, got you. Our SUT uses : https://www.npmjs.com/package/kafka-streams to create factories to run streams in order to read and write. The current code is not fitted to be called inside a synchronousBodyHandler on consumer side neither on providerWithMetadata provider side. We are currently looking on how to refactor our code to make it PACT compatible. Any advices/suggestions will be welcomed.

there is no Pact function that takes a stream. I think you’ll need to create your own function

Hello Matt I have successfully completed the consumer test, moving to the provider. My provider starts by sending an API post request ti create an object. That API call will then trigger a function to publish the created message into a kafka-topic. My question here is should I got through the API in my test provider or should I directly target the function that publishes the message in KAFKA? I am asking since in the message example in pact js it seems that it's : https://github.com/pact-foundation/pact-js/blob/master/examples/messages/provider/message-provider.spec.ts going through the API

This is example doesn’t test an API - it directly registers a function (e.g. the “directly target the function”): https://github.com/pact-foundation/pact-js/blob/master/examples/messages/provider/message-provider.spec.ts#L14 It’s OK if you have an API if that’s the easiest way to make it work, but ideally you hit the fn directly

Thanks Matt, in my case the provider function would be the one that write a Stream to a specific kafka topic 🙂 that's what I am trying to implement now.