Parallel execution for RSpec and Browserstack

parallel_rspec.rb

desc 'Runs Selenium Tests in browserstack in parallel'
task :browserstack_spec_parallel, [:opts] do |t, args|
  puts "Running with: #{@browser.inspect}"
  setup_browserstack_variables(@browser)

  begin
    # Get all files
    pattern = args[:opts].split('--pattern')[-1].split(' ')[0].gsub('"', '')
    test_files = FileList[pattern].shuffle

    # Slice the test files to evenly distribute amongst forks
    test_files_sliced = test_files.each_slice(test_files.length / @forks).to_a

    #Adjust for slices with remainders
    if test_files.length % @forks != 0
      test_files_sliced = adjust_slices(test_files_sliced)
    end

    pids = []
    @forks.times do |i|
      pids << fork do
        begin
          puts "Fork #{i} testing #{test_files_sliced[i].join(", ")}"

          #Setup unique job
          RSpec::Core::RakeTask.new("spec#{i}", :opts) do |t, args|
            t.rspec_opts = strip_quotes(args)
          end

          # Adjust Options, remove pattern for unique job
          opts = remove_pattern(args[:opts])
          opts = strip_quotes(opts)
          if opts.include? 'rspec_results.html'
            opts = opts.gsub('rspec_results.html', "rspec_results[#{i}].html")
          end

          #Add files to rspec args
          test_files_sliced[i].each { |file|
            opts = opts << " #{file.to_s}"
          }

          sio = redirect_stdout

          # Run the test
          Rake::Task["spec#{i}"].execute(opts)

        rescue => ex
          sio << "\n#{ex.message}\n#{ex.backtrace.join("\t\n")}"
        ensure

          # reset stdout
          $stdout = STDOUT

          # Output the test results
          puts "Fork #{i} completed, output:"
          puts "Testing:\n#{test_files_sliced[i].join(", ")}\n"
          sio.rewind
          puts sio.read

          # Force the fork to end without running at_exit bindings
          Kernel.exit!
        end
      end
    end
    Process.waitall
  rescue => e
    puts e.message
    puts e.backtrace.join("\n\t")
  end
end

#------ rake/utilities.rb ----------

def redirect_stdout
  sio = StringIO.new
  $stdout = sio
  $stderr = sio
  return sio
end

def adjust_slices(test_files_sliced)
    test_files_sliced[0] << test_files_sliced[-1]
    return test_files_sliced[0..test_files_sliced.size-2]
end