some_spec.rb

# Add somewhere inside you spec file

require 'ruby_parser'

RSpec.configure do |config|
  config.after(:suite) do
    # Calling compare_traces after all suites complete
    compare_traces('trace_with_feature_on.txt', 'trace_with_feature_off.txt')
  end
end


SKIP_FILES = Set.new([
  '/app/config/initializers/active_record_custom_preloader.rb',
  # you can add more file to skip them from trace tracker
]);

def trace_diff(file_name)
  traces = []
  trace = TracePoint.new(:line) do |tp|
    next unless tp.path.include?('/app/')
    next if tp.path.include?('/app/spec')
    next if SKIP_FILES.include?(tp.path)
    traces << [tp.path, tp.lineno]
  end

  trace.enable
  yield
  trace.disable

  files = {}

  File.open(file_name, 'w') do |file|
    width = 60
    traces.each do |tp|
      files[tp[0]] ||= File.readlines(tp[0])
      line_content = files[tp[0]][tp[1] - 1].strip
      offset = ' ' * [width - tp[0].size - tp[1].to_s.size, 1].max
      file.puts "#{tp[0]}:#{tp[1]}#{offset}#{line_content}:"
    end
  end
end

def compare_traces(file1, file2)
  return if !File.exists?(file1) || !File.exists?(file2)
  trace1 = File.readlines(file1)
  trace2 = File.readlines(file2)

  trace1.zip(trace2).each_with_index do |(line1, line2), index|
    if line1 != line2
      start_line = [0, index - 5].max
      middle_line = index
      end_line = [index + 5, trace1.size - 1].min

      puts "Расхождение обнаружено на строке #{index + 1}"
      puts "Фрагмент из файла #{file1}:"
      puts trace1[start_line...middle_line].join
      puts ">>>#{trace1[middle_line]}"
      puts trace1[1 + middle_line..end_line].join

      puts "\nФрагмент из файла #{file2}:"
      puts trace2[start_line...middle_line].join
      puts ">>>#{trace2[middle_line]}"
      puts trace2[1 + middle_line..end_line].join
      break
    end
  end
end

it do
  trace_diff('trace_with_feature_off.txt) do
    action
  end
end

it do
  Flipper[...].enable
  trace_diff('trace_with_feature_on.txt) do
    action
  end
end