class ActiveSupport::Testing::ParallelizeExecutor

def <<(work)
  parallel_executor << work if parallelized?
end

def build_parallel_executor
  case parallelize_with
  when :processes
    Testing::Parallelization.new(size)
  when :threads
    ActiveSupport::TestCase.lock_threads = false if defined?(ActiveSupport::TestCase.lock_threads)
    Minitest::Parallel::Executor.new(size)
  else
    raise ArgumentError, "#{parallelize_with} is not a supported parallelization executor."
  end
end

def execution_info
  if parallelized?
    "Running #{tests_count} tests in parallel using #{parallel_executor.size} #{parallelize_with}"
  else
    "Running #{tests_count} tests in a single process (parallelization threshold is #{threshold})"
  end
end

def initialize(size:, with:, threshold: ActiveSupport.test_parallelization_threshold)
  @size = size
  @parallelize_with = with
  @threshold = threshold
end

def parallel_executor
  @parallel_executor ||= build_parallel_executor
end

def parallelize
  @parallelized = true
  Minitest::Test.parallelize_me!
end

def parallelized?
  @parallelized if defined?(@parallelized)
end

def should_parallelize?
  ENV["PARALLEL_WORKERS"] || tests_count > threshold
end

def show_execution_info
  puts execution_info
end

def shutdown
  parallel_executor.shutdown if parallelized?
end

def start
  parallelize if should_parallelize?
  show_execution_info
  parallel_executor.start if parallelized?
end

def tests_count
  @tests_count ||= Minitest::Runnable.runnables.sum { |runnable| runnable.runnable_methods.size }
end