module SimpleCov::Combine::ResultsCombiner

def combine(*results)
  initial = {} #: Hash[untyped, untyped]
  results.reduce(initial) do |combined_results, next_result|
    combine_result_sets(combined_results, next_result)
  end
end

def combine_file_coverage(coverage_a, coverage_b)
  Combine.combine(Combine::FilesCombiner, coverage_a, coverage_b)
end

def combine_result_sets(combined_results, result)
  results_files = combined_results.keys | result.keys
  results_files.to_h do |file_name|
    [file_name, combine_file_coverage(
      combined_results[file_name],
      result[file_name]
    )]
  end
end