rails/actioncable/lib/action_cable/test_helper.rb

# frozen_string_literal: true

module ActionCable
  # Provides helper methods for testing Action Cable broadcasting
  module TestHelper
    def before_setup # :nodoc:
      server = ActionCable.server
      test_adapter = ActionCable::SubscriptionAdapter::Test.new(server)

      @old_pubsub_adapter = server.pubsub

      server.instance_variable_set(:@pubsub, test_adapter)
      super
    end

    def after_teardown # :nodoc:
      super
      ActionCable.server.instance_variable_set(:@pubsub, @old_pubsub_adapter)
    end

    # Asserts that the number of broadcasted messages to the stream matches the given number.
    #
    #   def test_broadcasts
    #     assert_broadcasts 'messages', 0
    #     ActionCable.server.broadcast 'messages', { text: 'hello' }
    #     assert_broadcasts 'messages', 1
    #     ActionCable.server.broadcast 'messages', { text: 'world' }
    #     assert_broadcasts 'messages', 2
    #   end
    #
    # If a block is passed, that block should cause the specified number of
    # messages to be broadcasted. It returns the messages that were broadcasted.
    #
    #   def test_broadcasts_again
    #     message = assert_broadcasts('messages', 1) do
    #       ActionCable.server.broadcast 'messages', { text: 'hello' }
    #     end
    #     assert_equal({ text: 'hello' }, message)
    #
    #     messages = assert_broadcasts('messages', 2) do
    #       ActionCable.server.broadcast 'messages', { text: 'hi' }
    #       ActionCable.server.broadcast 'messages', { text: 'how are you?' }
    #     end
    #     assert_equal 2, messages.length
    #     assert_equal({ text: 'hi' }, messages.first)
    #     assert_equal({ text: 'how are you?' }, messages.last)
    #   end
    #
    def assert_broadcasts(stream, number, &block)
      if block_given?
        new_messages = new_broadcasts_from(broadcasts(stream), stream, "assert_broadcasts", &block)

        actual_count = new_messages.size
        assert_equal number, actual_count, "#{number} broadcasts to #{stream} expected, but #{actual_count} were sent"

        if new_messages.size == 1
          ActiveSupport::JSON.decode(new_messages.first)
        else
          new_messages.map { |m| ActiveSupport::JSON.decode(m) }
        end
      else
        actual_count = broadcasts(stream).size
        assert_equal number, actual_count, "#{number} broadcasts to #{stream} expected, but #{actual_count} were sent"
      end
    end

    # Asserts that no messages have been sent to the stream.
    #
    #   def test_no_broadcasts
    #     assert_no_broadcasts 'messages'
    #     ActionCable.server.broadcast 'messages', { text: 'hi' }
    #     assert_broadcasts 'messages', 1
    #   end
    #
    # If a block is passed, that block should not cause any message to be sent.
    #
    #   def test_broadcasts_again
    #     assert_no_broadcasts 'messages' do
    #       # No job messages should be sent from this block
    #     end
    #   end
    #
    # Note: This assertion is simply a shortcut for:
    #
    #   assert_broadcasts 'messages', 0, &block
    #
    def assert_no_broadcasts(stream, &block)
      assert_broadcasts stream, 0, &block
    end

    # Asserts that the specified message has been sent to the stream.
    #
    #   def test_assert_transmitted_message
    #     ActionCable.server.broadcast 'messages', text: 'hello'
    #     assert_broadcast_on('messages', text: 'hello')
    #   end
    #
    # If a block is passed, that block should cause a message with the specified data to be sent.
    #
    #   def test_assert_broadcast_on_again
    #     assert_broadcast_on('messages', text: 'hello') do
    #       ActionCable.server.broadcast 'messages', text: 'hello'
    #     end
    #   end
    #
    def assert_broadcast_on(stream, data, &block)
      # Encode to JSON and back–we want to use this value to compare
      # with decoded JSON.
      # Comparing JSON strings doesn't work due to the order if the keys.
      serialized_msg =
        ActiveSupport::JSON.decode(ActiveSupport::JSON.encode(data))

      new_messages = broadcasts(stream)
      if block_given?
        new_messages = new_broadcasts_from(new_messages, stream, "assert_broadcast_on", &block)
      end

      message = new_messages.find { |msg| ActiveSupport::JSON.decode(msg) == serialized_msg }

      error_message = "No messages sent with #{data} to #{stream}"

      if new_messages.any?
        error_message = new_messages.inject("#{error_message}\nMessage(s) found:\n") do |error_message, new_message|
          error_message + "#{ActiveSupport::JSON.decode(new_message)}\n"
        end
      else
        error_message = "#{error_message}\nNo message found for #{stream}"
      end

      assert message, error_message
    end

    def pubsub_adapter # :nodoc:
      ActionCable.server.pubsub
    end

    delegate :broadcasts, :clear_messages, to: :pubsub_adapter

    private
      def new_broadcasts_from(current_messages, stream, assertion, &block)
        old_messages = current_messages
        clear_messages(stream)

        _assert_nothing_raised_or_warn(assertion, &block)
        new_messages = broadcasts(stream)
        clear_messages(stream)

        # Restore all sent messages
        (old_messages + new_messages).each { |m| pubsub_adapter.broadcast(stream, m) }

        new_messages
      end
  end
end