Module: Karafka::Testing::RSpec::Helpers

Defined in:
lib/karafka/testing/rspec/helpers.rb

Overview

RSpec helpers module that needs to be included

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(base) ⇒ Object

Adds all the needed extra functionalities to the rspec group

Parameters:

  • base (Class) —

    RSpec example group we want to extend



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# File 'lib/karafka/testing/rspec/helpers.rb', line 29

def included(base)
  # RSpec local reference to Karafka proxy that allows us to build the consumer instance
  base.let(:karafka) { Karafka::Testing::RSpec::Proxy.new(self) }

  # Messages that are targeted to the consumer
  # You can produce many messages from Karafka during specs and not all should go to the
  # consumer for processing. This buffer holds only those that should go to consumer
  base.let(:_karafka_consumer_messages) { [] }
  # Consumer fake client to mock communication with Kafka
  base.let(:_karafka_consumer_client) { Karafka::Testing::SpecConsumerClient.new }
  # Producer fake client to mock communication with Kafka
  base.let(:_karafka_producer_client) { Karafka::Testing::SpecProducerClient.new(self) }

  base.before(:context) do
    Karafka::Testing.ensure_karafka_initialized!
    @_karafka_shared_producer_client = WaterDrop::Clients::Dummy.new(-1)
    Karafka.producer.instance_variable_set(:@client, @_karafka_shared_producer_client)
    Karafka.producer.instance_variable_set(:@pid, ::Process.pid)
  end

  base.prepend_before do
    _karafka_consumer_messages.clear
    _karafka_producer_client.reset
    @_karafka_consumer_mappings = {}

    # We do check the presence not only of Mocha but also that it is used and
    # that patches are available because some users have Mocha as part of their
    # supply chain, but do not use it when running Karafka specs. In such cases, without
    # such check `karafka-testing` would falsely assume, that Mocha is in use.
    if Object.const_defined?('Mocha', false) && Karafka.producer.respond_to?(:stubs)
      Karafka.producer.stubs(:client).returns(_karafka_producer_client)
    else
      allow(Karafka.producer).to receive(:client).and_return(_karafka_producer_client)
    end
  end
end

Instance Method Details

#_karafka_add_message_to_consumer_if_needed(message) ⇒ Object

Adds a new Karafka message instance if needed with given payload and options into an internal consumer buffer that will be used to simulate messages delivery to the consumer

Examples:

Send a json message to consumer

before do
  karafka.produce({ 'hello' => 'world' }.to_json)
end

Send a json message to consumer and simulate, that it is partition 6

before do
  karafka.produce({ 'hello' => 'world' }.to_json, 'partition' => 6)
end

Parameters:

  • message (Hash) —

    message that was sent to Kafka



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# File 'lib/karafka/testing/rspec/helpers.rb', line 106

def _karafka_add_message_to_consumer_if_needed(message)
  consumer_obj = if defined?(consumer)
                   consumer
                 else
                   _karafka_find_consumer_for_message(message)
                 end
  # Consumer needs to be defined in order to pass messages to it
  return unless consumer_obj
  # We're interested in adding message to consumer only when it is a Karafka consumer
  # Users may want to test other things (models producing messages for example) and in
  # their case consumer will not be a consumer
  return unless consumer_obj.is_a?(Karafka::BaseConsumer)
  # We target to the consumer only messages that were produced to it, since specs may also
  # produce other messages targeting other topics
  return unless message[:topic] == consumer_obj.topic.name
  # If consumer_group is explicitly specified, verify it matches
  return if message[:consumer_group] &&
            message[:consumer_group].to_s != consumer_obj.topic.consumer_group.name

  # Build message metadata and copy any metadata that would come from the message
  metadata = _karafka_message_metadata_defaults(consumer_obj)

  metadata.keys.each do |key|
    message_key = METADATA_DISPATCH_MAPPINGS.fetch(key, key)

    next unless message.key?(message_key)

    metadata[key] = message.fetch(message_key)
  end

  # Add this message to previously produced messages
  _karafka_consumer_messages << Karafka::Messages::Message.new(
    message[:payload],
    Karafka::Messages::Metadata.new(metadata)
  )

  # Update batch metadata
  batch_metadata = Karafka::Messages::Builders::BatchMetadata.call(
    _karafka_consumer_messages,
    consumer_obj.topic,
    0,
    Time.now
  )

  # Update consumer messages batch
  consumer_obj.messages = Karafka::Messages::Messages.new(
    _karafka_consumer_messages,
    batch_metadata
  )
end

#_karafka_consumer_for(requested_topic, requested_consumer_group = nil) ⇒ Object

Creates a consumer instance for a given topic

Examples:

Creates a MyConsumer consumer instance with settings for ‘my_requested_topic`

RSpec.describe MyConsumer do
  subject(:consumer) { karafka.consumer_for(:my_requested_topic) }
end

Parameters:

  • requested_topic (String, Symbol) —

    name of the topic for which we want to create a consumer instance

  • requested_consumer_group (String, Symbol, nil) (defaults to: nil) —

    optional name of the consumer group if we have multiple consumer groups listening on the same topic

Returns:

  • (Object) —

    Karafka consumer instance

Raises:



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# File 'lib/karafka/testing/rspec/helpers.rb', line 81

def _karafka_consumer_for(requested_topic, requested_consumer_group = nil)
  selected_topics = Testing::Helpers.karafka_consumer_find_candidate_topics(
    requested_topic.to_s,
    requested_consumer_group.to_s
  )

  raise Errors::TopicInManyConsumerGroupsError, requested_topic if selected_topics.size > 1
  raise Errors::TopicNotFoundError, requested_topic if selected_topics.empty?

  _karafka_build_consumer_for(selected_topics.first)
end

#_karafka_produce(payload, metadata = {}) ⇒ Object

Produces message with a given payload to the consumer matching topic

Parameters:

  • payload (String) —

    payload we want to dispatch

  • metadata (Hash) (defaults to: {}) —

    any metadata we want to dispatch alongside the payload



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# File 'lib/karafka/testing/rspec/helpers.rb', line 160

def _karafka_produce(payload, metadata = {})
  topic = if metadata[:topic]
            metadata[:topic]
          elsif defined?(consumer)
            consumer.topic.name
          else
            last_consumer = @_karafka_consumer_mappings&.values&.last
            last_consumer&.topic&.name
          end
  Karafka.producer.produce_sync(
    {
      topic: topic,
      payload: payload
    }.merge(metadata)
  )
end

#_karafka_produce_to(consumer_instance, payload, metadata = {}) ⇒ Object

Produces message to a specific consumer instance Use when testing multiple consumers for the same topic

Examples:

Produce to specific consumer when multiple exist for same topic

let(:consumer1) { karafka.consumer_for(:events, :analytics_group) }
let(:consumer2) { karafka.consumer_for(:events, :notifications_group) }

before do
  karafka.produce_to(consumer1, { 'event' => 'click' }.to_json)
end

Parameters:

  • consumer_instance (Object) —

    the consumer to produce to

  • payload (String) —

    message content (usually serialized JSON) to deliver to the consumer

  • metadata (Hash) (defaults to: {}) —

    any metadata to dispatch alongside the payload



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# File 'lib/karafka/testing/rspec/helpers.rb', line 197

def _karafka_produce_to(consumer_instance, payload, metadata = {})
  _karafka_produce(
    payload,
    metadata.merge(
      topic: consumer_instance.topic.name,
      consumer_group: consumer_instance.topic.consumer_group.name
    )
  )
end

#_karafka_produced_messages ⇒ Array<Hash>

Returns messages that were produced.

Returns:

  • (Array<Hash>) —

    messages that were produced



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# File 'lib/karafka/testing/rspec/helpers.rb', line 178

def _karafka_produced_messages
  _karafka_producer_client.messages
end