Jenkins CI Rake Task with Parallel Tests

ci.rake

namespace :ci do
  desc 'Run rubocop for CI environment'
  task :rubocop do
    args = %w{
      --require ./lib/rubocop/formatter/progress_formatter_no_report
      --format Rubocop::Formatter::ProgressFormatterNoReport
      --require rubocop/formatter/checkstyle_formatter
      --format Rubocop::Formatter::CheckstyleFormatter
      --rails
      --fail-level error
      --out tmp/checkstyle-result.xml
    }
    sh 'rubocop', *args
  end

  desc 'Run brakeman for CI environment'
  task :brakeman do
    args = %w{
      --no-progress
      --exit-on-warn
      --output tmp/brakeman-output.tabs
      --output tmp/brakeman-output.txt
    }.join ' '
    cmd = %(brakeman #{args} 2>&1 | awk '{ print "."; fflush() } END { print "\\n" }' ORS=)
    sh *%W(bash -o pipefail -c #{cmd}) do |ok, result|
      unless ok
        report = Pathname('tmp/brakeman-output.txt')
        error = "Brakeman check failed with exit code #{result.exitstatus}:\n"
        error << report.read if report.exist?
        fail error
      end
    end
  end

  task :build => :cleanup do
    ENV['CI'] = '1'
    jobs = Rake.application.options.thread_pool_size.to_i + 1
    if jobs > 1
      ENV['DISABLE_SPRING'] = '1'
      ENV['PARALLEL_TEST_PROCESSORS'] ||= jobs.to_s
      Rake::Task['ci:prepare_parallel'].invoke
      Rake::MultiTask['ci:run_parallel'].invoke
    else
      ENV['SPEC'] = '-O spec/spec.opts spec'
      Rake::Task['ci:prepare'].invoke
      Rake::Task['ci:run'].invoke
    end
  end

  desc 'Remove artifacts created by CI run'
  task :cleanup do
    files = Dir.glob '{
      tmp/checkstyle-result.xml,
      tmp/brakeman-output.*,
      tmp/rspec-report*.xml,
      tmp/failing_specs.log,
      tmp/spec_summary.log
    }'.gsub /\s+/, ''
    rm files if files.any?
  end

  task :prepare => ['secrets', 'db:create', 'db:migrate', 'db:export_test:reset']
  task :prepare_parallel => ['secrets', 'db:create', 'db:migrate', 'parallel:create', 'parallel:prepare', 'parallel:export_test:reset']

  task :run => [:brakeman, :rubocop, 'spec']
  multitask :run_parallel => [:brakeman, :rubocop, 'parallel:spec']
end

desc 'Run the full CI suite (use --jobs <n> for parallel run)'
task :ci => 'ci:build'

Parallel execution requires running rake --jobs <n> ci.