rspec retry mechanism

my_fake_tests_spec.rb

describe 'my fake tests', :type => :feature do

  it 'this scenario should pass' do
    expect(true).to eq true
  end

  it 'this scenario should fail' do
    expect(false).to eq true
  end
end

rake rspec_with_retries[3]

require 'fileutils'
require 'childprocess'

task :rspec_with_retries, [:max_tries] do |_, args|
  max_tries = args[:max_tries].to_i

  # exit hook to ensure rspec process gets stopped when CTRL+C (SIGTERM is pressed)
  # needs to be set outside the times loop as otherwise each iteration would add its
  # own at_exit hook
  process = nil
  at_exit do
    process.stop unless process.nil?
  end

  # construct initial rspec command
  command = ['bundle', 'exec', 'rspec', '--require', './spec/formatters/failure_formatter.rb', '--format', 'FailureFormatter', '--no-fail-fast']

  max_tries.times do |t|
    puts "\n"
    puts '##########'
    puts "### STARTING TEST RUN #{t + 1} OUT OF A MAXIMUM OF #{max_tries}"
    puts "### executing command: #{command}"
    puts '##########'

    # delete tests_failed file left over by previous run
    FileUtils.rm('tests_failed', :force => true)

    # run tests in separate process
    process = ChildProcess.build(*command)
    process.io.inherit!
    process.start
    process.wait

    # early out
    exit 0 if process.exit_code.zero?
    exit 1 if (t == max_tries - 1)

    # determine which tests need to be run again
    failed_tests = []
    File.open('tests_failed', 'r') do |file|
      failed_tests = file.readlines.map { |line| line.strip }
    end

    # construct command to rerun just the failed tests
    command  = ['bundle', 'exec', 'rspec']
    command += Array.new(failed_tests.length, '-e').zip(failed_tests).flatten
    command += ['--require', './spec/formatters/failure_formatter.rb', '--format', 'FailureFormatter', '--no-fail-fast']
  end
end

spec formatters failure_formatter.rb

require 'rspec/core/formatters/progress_formatter'

class FailureFormatter < RSpec::Core::Formatters::ProgressFormatter
  RSpec::Core::Formatters.register self, :example_failed

  def example_failed(notification)
    super
    File.open('tests_failed', 'a') do |file|
      file.puts(notification.example.full_description)
    end
  end
end