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require 'active_support/log_subscriber'
require 'active_support/logger'
require 'active_support/notifications'
module ActiveSupport
class LogSubscriber
# Provides some helpers to deal with testing log subscribers by setting up
# notifications. Take for instance Active Record subscriber tests:
#
# class SyncLogSubscriberTest < ActiveSupport::TestCase
# include ActiveSupport::LogSubscriber::TestHelper
#
# setup do
# ActiveRecord::LogSubscriber.attach_to(:active_record)
# end
#
# def test_basic_query_logging
# Developer.all.to_a
# wait
# assert_equal 1, @logger.logged(:debug).size
# assert_match(/Developer Load/, @logger.logged(:debug).last)
# assert_match(/SELECT \* FROM "developers"/, @logger.logged(:debug).last)
# end
# end
#
# All you need to do is to ensure that your log subscriber is added to
# Rails::Subscriber, as in the second line of the code above. The test
# helpers are responsible for setting up the queue, subscriptions and
# turning colors in logs off.
#
# The messages are available in the @logger instance, which is a logger with
# limited powers (it actually does not send anything to your output), and
# you can collect them doing @logger.logged(level), where level is the level
# used in logging, like info, debug, warn and so on.
module TestHelper
def setup # :nodoc:
@logger = MockLogger.new
@notifier = ActiveSupport::Notifications::Fanout.new
ActiveSupport::LogSubscriber.colorize_logging = false
@old_notifier = ActiveSupport::Notifications.notifier
set_logger(@logger)
ActiveSupport::Notifications.notifier = @notifier
end
def teardown # :nodoc:
set_logger(nil)
ActiveSupport::Notifications.notifier = @old_notifier
end
class MockLogger
include ActiveSupport::Logger::Severity
attr_reader :flush_count
attr_accessor :level
def initialize(level = DEBUG)
@flush_count = 0
@level = level
@logged = Hash.new { |h,k| h[k] = [] }
end
def method_missing(level, message = nil)
if block_given?
@logged[level] << yield
else
@logged[level] << message
end
end
def logged(level)
@logged[level].compact.map { |l| l.to_s.strip }
end
def flush
@flush_count += 1
end
ActiveSupport::Logger::Severity.constants.each do |severity|
class_eval <<-EOT, __FILE__, __LINE__ + 1
def #{severity.downcase}?
#{severity} >= @level
end
EOT
end
end
# Wait notifications to be published.
def wait
@notifier.wait
end
# Overwrite if you use another logger in your log subscriber.
#
# def logger
# ActiveRecord::Base.logger = @logger
# end
def set_logger(logger)
ActiveSupport::LogSubscriber.logger = logger
end
end
end
end