Karafka Testing library

Karafka-Testing is a library that provides RSpec helpers, to make testing of Karafka consumers much easier.

Installation

Add this gem to your Gemfile in the test group:

group :test do
  gem 'karafka-testing'
  gem 'rspec'
end

and then in your spec_helper.rb file:

require 'karafka/testing/rspec/helpers'

RSpec.configure do |config|
  config.include Karafka::Testing::RSpec::Helpers
end

Usage

Once included into your RSpec setup, this library will provide you two methods that you can use with your specs:

• #karafka_consumer_for - this method will create a consumer instance for the desired topic. It needs to be set as the spec subject.
• #publish_for_karafka - this method will "send" message to the consumer instance.

Note: Messages sent using the #publish_for_karafka method won't be sent to Kafka. They will be "virtually" delegated to the created consumer instance so your specs can run without Kafka setup.

RSpec.describe InlineBatchConsumer do
  # This will create a consumer instance with all the settings defined for the given topic
  subject(:consumer) { karafka_consumer_for(:inline_batch_data) }

  let(:nr1_value) { rand }
  let(:nr2_value) { rand }
  let(:sum) { nr1_value + nr2_value }

  before do
    # Sends first message to Karafka consumer
    publish_for_karafka({ 'number' => nr1_value }.to_json)
    # Sends second message to Karafka consumer
    publish_for_karafka({ 'number' => nr2_value }.to_json)
    allow(Karafka.logger).to receive(:info)
  end

  it 'expects to log a proper message' do
    expect(Karafka.logger).to receive(:info).with("Sum of 2 elements equals to: #{sum}")
    consumer.consume
  end
end

Note on contributions

First, thank you for considering contributing to the Karafka ecosystem! It's people like you that make the open source community such a great community!

Each pull request must pass all the RSpec specs, integration tests and meet our quality requirements.

Fork it, update and wait for the Github Actions results.