Simple ActiveRecord query counter

test_case.rb

class TestCase < ActiveSupport::TestCase
  def setup
    super
    DatabaseCleaner.start
    @queries = []

    ActiveSupport::Notifications.subscribe('sql.active_record') do |_, _, _, _, payload|
      @queries << payload[:sql] unless payload[:name].in? %w[CACHE SCHEMA]
    end
  end

  def teardown
    DatabaseCleaner.clean
    super
  end

  def assert_query_count(expected_count)
    before_count = 0

    if block_given?
      before_count = @queries.length
      yield
    end

    actual_count = @queries.length - before_count
    assert_equal expected_count, actual_count, @queries[before_count...].join("\n")
  end
end