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



19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
 
# File 'lib/karafka/testing/rspec/helpers.rb', line 19

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.prepend_before do
    _karafka_consumer_messages.clear
    _karafka_producer_client.reset

    if Object.const_defined?('Mocha', false)
      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



84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
 
# File 'lib/karafka/testing/rspec/helpers.rb', line 84

def _karafka_add_message_to_consumer_if_needed(message)
  # Consumer needs to be defined in order to pass messages to it
  return unless defined?(consumer)
  # 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.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.topic.name

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

  metadata.keys.each do |key|
    next unless message.key?(key)

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

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

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

  # Update consumer messages batch
  consumer.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:



59
60
61
62
63
64
65
66
67
68
69
 
# File 'lib/karafka/testing/rspec/helpers.rb', line 59

def _karafka_consumer_for(requested_topic, requested_consumer_group = nil)
  selected_topics = _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



128
129
130
131
132
133
134
135
 
# File 'lib/karafka/testing/rspec/helpers.rb', line 128

def _karafka_produce(payload, metadata = {})
  Karafka.producer.produce_sync(
    {
      topic: consumer.topic.name,
      payload: payload
    }.merge(metadata)
  )
end

#_karafka_produced_messages ⇒ Array<Hash>

Returns messages that were produced.

Returns:

  • (Array<Hash>) —

    messages that were produced



138
139
140
 
# File 'lib/karafka/testing/rspec/helpers.rb', line 138

def _karafka_produced_messages
  _karafka_producer_client.messages
end