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Testing Service Discovery Manager Implementation in Fluentd

This test suite validates the ServiceDiscoveryManager functionality in Fluentd, focusing on service configuration management and dynamic service updates. It ensures proper handling of service discovery plugins and their integration with the core manager component.

Test Coverage Overview

The test suite provides comprehensive coverage of the ServiceDiscoveryManager’s core functionality:

Configuration handling for multiple service discovery plugins
Static and dynamic service management
Service addition and removal operations
Integration with custom service discovery plugins

Implementation Analysis

The testing approach utilizes Test::Unit framework with mock objects to validate service discovery behavior. It implements sub-test cases for isolated testing of configuration and runtime operations, using a custom TestSdPlugin for service simulation.

Mock-based service discovery plugin testing
Sub-test case organization for focused testing
Configuration element validation

Technical Details

Test::Unit as the primary testing framework
RR for mocking functionality
Custom TestSdPlugin implementation
File-based configuration testing
Service discovery message queue implementation

Best Practices Demonstrated

The test suite exemplifies robust testing practices through structured test organization and comprehensive validation approaches.

Isolated test cases for specific functionality
Proper test setup and teardown
Mock object usage for external dependencies
Clear assertion patterns
Edge case coverage

fluent/fluentd

test/plugin_helper/service_discovery/test_manager.rb

            
require_relative '../../helper'
require 'fluent/plugin_helper/service_discovery/manager'

class TestServiceDiscoveryManager < ::Test::Unit::TestCase
  setup do
    @sd_file_dir = File.expand_path('../../plugin/data/sd_file', __dir__)
  end

  class TestSdPlugin < Fluent::Plugin::ServiceDiscovery
    Fluent::Plugin.register_sd('test_sd', self)

    def initialize
      super
    end

    def service_in(host, port)
      s = Fluent::Plugin::ServiceDiscovery::Service.new(:sd_test, host, port)
      @queue << Fluent::Plugin::ServiceDiscovery.service_in_msg(s)
    end

    def service_out(host, port)
      s = Fluent::Plugin::ServiceDiscovery::Service.new(:sd_test, host, port)
      @queue << Fluent::Plugin::ServiceDiscovery.service_out_msg(s)
    end

    def start(queue)
      @queue = queue

      super
    end
  end

  sub_test_case '#configure' do
    test 'build sd plugins and services' do
      sdm = Fluent::PluginHelper::ServiceDiscovery::Manager.new(log: $log)
      sdm.configure(
        [
          { type: :file, conf: config_element('service_discovery', '', { 'path' => File.join(@sd_file_dir, 'config.yml') }) },
          { type: :static, conf: config_element('root', '', {}, [config_element('service', '', { 'host' => '127.0.0.2', 'port' => '5432' })]) },
        ],
      )

      assert_equal 3, sdm.services.size
      assert_equal 24224, sdm.services[0].port
      assert_equal '127.0.0.1', sdm.services[0].host

      assert_equal 24225, sdm.services[1].port
      assert_equal '127.0.0.1', sdm.services[1].host

      assert_equal 5432, sdm.services[2].port
      assert_equal '127.0.0.2', sdm.services[2].host

      assert_false sdm.static_config?
    end

    test 'no need to timer if only static' do
      sdm = Fluent::PluginHelper::ServiceDiscovery::Manager.new(log: $log)
      sdm.configure(
        [{ type: :static, conf: config_element('root', '', {}, [config_element('service', '', { 'host' => '127.0.0.2', 'port' => '5432' })]) }]
      )

      assert_equal 1, sdm.services.size
      assert_equal 5432, sdm.services[0].port
      assert_equal '127.0.0.2', sdm.services[0].host

      assert_true sdm.static_config?
    end
  end

  sub_test_case '#run_once' do
    test 'if new service added and deleted' do
      sdm = Fluent::PluginHelper::ServiceDiscovery::Manager.new(log: $log)
      t = TestSdPlugin.new
      mock(Fluent::Plugin).new_sd(:sd_test, parent: anything) { t }
      sdm.configure([{ type: :sd_test, conf: config_element('service_discovery', '', {})}])
      sdm.start

      assert_equal 0, sdm.services.size

      t.service_in('127.0.0.1', '1234')

      sdm.run_once
      assert_equal 1, sdm.services.size
      assert_equal '127.0.0.1', sdm.services[0].host
      assert_equal '1234', sdm.services[0].port

      t.service_out('127.0.0.1', '1234')

      sdm.run_once
      assert_equal 0, sdm.services.size
    end
  end
end