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    kafka-test-helper
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    1.1.0 • Public • Published

    kafka-test-helper

    Kafka test helper is a Node.js library that helps you writing integration tests that interacts with Apache Kafka.

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    Features

    This library can:

    • read events published on a topic
    • publish events on a channel or a specific partition
    • create/delete topic on the fly

    Kafka test helper is able to work both with independent messages and messages managed in the context of a transaction (commited or aborted). You can use Kafka test helper in conjunction with your preferred testing library, because it is compatible with jest, mocha, tap and so on..., by the way it's agnostic by test runners.

    Documentation

    Install

    npm install kafka-test-helper

    Examples

    Testing a producer

    Full source code available here: ProducerExample.test.js and ProducerExample.js

    import { createKafkaTestHelper } from 'kafka-test-helper'
    
    test('ProducerExample', async () => {
      // init Kafka Test helper
      const kafka = getKafka() // see https://kafka.js.org/docs/configuration
      const topicPrefix = Date.now() //  this avoids cross test interference
      const topicHelper = await createKafkaTestHelper(kafka, topicPrefix + '_something_happened')
      await topicHelper.ensureTopicExists()
    
      // init the module that has to be tested
      const controller = new ProducerExample()
      await controller.setup(kafka, topicPrefix)
    
      const record = {
        name: 'Tony',
        surname: 'Stark'
      }
    
      await controller.doSomething(record)
    
      // Kafka Test Helper retrieves published messages
      const messages = await topicHelper.messages()
      expect(messages).toHaveLength(1)
      expect(messages[0].json).toEqual({
        operation: 'doSomething',
        record
      })
    
      // OR
      expect(messages[0].string).toEqual(JSON.stringify({
        operation: 'doSomething',
        record
      }))
    
      // OR
      expect(messages[0].buffer).toEqual(Buffer.from(JSON.stringify({
        operation: 'doSomething',
        record
      })))
    
      // OR
      expect(messages).toEqual([
        expect.objectContaining({
          json: {
            operation: 'doSomething',
            record
          }
        })
      ])
    
      // destroy
      await controller.destroy()
      await topicHelper.ensureTopicDeleted()
    })

    Testing a consumer

    Full source code available here: ConsumerExample.test.js and ConsumerExample.js

    import { createKafkaTestHelper } from 'kafka-test-helper'
    
    test('ConsumerExample', async () => {
      // init Kafka Test helper
      const kafka = getKafka() // see https://kafka.js.org/docs/configuration
      const topicPrefix = Date.now() //  this avoids cross test interference
      const topicHelper = await createKafkaTestHelper(kafka, topicPrefix + 'test-topic')
      await topicHelper.ensureTopicExists()
    
      // init the module that has to be tested
      const controller = new ConsumerExample()
      await controller.setup(kafka, topicPrefix)
    
      // a way to intercepts when the controller has done (there could be other ways...)
      const waitMessage = () => new Promise(resolve => {
        controller.handleMessage = jest.fn()
          .mockImplementation(message => {
            resolve(message)
          })
      })
    
      // Kafka Test Helper publishes a message, serialized as JSON string
      await topicHelper.publishMessages([
        {
          json: {
            hello: 'world'
          }
        }
      ])
    
      // wait for post elaboration and validates output
      const message = await waitMessage()
      expect(message).toBe('{"hello":"world"}')
      await controller.destroy()
      await topicHelper.ensureTopicDeleted()
    })

    Changelog

    • 0.x - Beta version
    • 1.0 - First official version
    • 1.1 - Adds typescript definition [#1]; Upgrades deps

    Contributors

    References

    Keywords

    none

    Install

    npm i kafka-test-helper

    DownloadsWeekly Downloads

    7

    Version

    1.1.0

    License

    MIT

    Unpacked Size

    53.6 kB

    Total Files

    27

    Last publish

    Collaborators

    • chr.vadala