さすがにこれで完成ということにしたい

wc.rb

@@ -4,12 +4,12 @@ require 'optparse'
 
 def main
   options, filenames = parse_options
-  file_details = collect_file_stats(filenames)
-  total_stats = calculate_total_stats(file_details)
-  max_widths = calculate_max_widths(total_stats)
+  file_stats = collect_file_stats(filenames)
+  total_stat = calculate_total_stat(file_stats)
+  max_widths = calculate_max_widths(total_stat)
 
-  file_details.each { |file_stats| print_stats(file_stats, max_widths, options) }
-  print_stats(total_stats, max_widths, options) if filenames.size > 1
+  file_stats << total_stat if filenames.size > 1
+  file_stats.each { |file_stat| puts format_result(file_stat, max_widths, options).join(' ') }
 end
 
 def parse_options
@@ -27,32 +27,34 @@ end
 def collect_file_stats(filenames)
   filenames.map do |filename|
     text = filename.empty? ? ARGF.read : File.read(filename)
-    { filename: filename, lines: text.lines.count, words: text.split.size, bytes: text.bytesize }
+    {
+      filename: filename,
+      lines: text.lines.count,
+      words: text.split.size,
+      bytes: text.bytesize
+    }
   end
 end
 
-def calculate_total_stats(file_details)
-  total_stats = { filename: '合計', lines: 0, words: 0, bytes: 0 }
-  file_details.each do |stats|
-    total_stats[:lines] += stats[:lines]
-    total_stats[:words] += stats[:words]
-    total_stats[:bytes] += stats[:bytes]
+def calculate_total_stat(file_stats)
+  total_stat = { filename: '合計', lines: 0, words: 0, bytes: 0 }
+  file_stats.each do |stats|
+    total_stat[:lines] += stats[:lines]
+    total_stat[:words] += stats[:words]
+    total_stat[:bytes] += stats[:bytes]
   end
-  total_stats
+  total_stat
 end
 
-def calculate_max_widths(total_stats)
-  %i[lines words bytes].to_h { |key| [key, total_stats[key].to_s.length] }
+def calculate_max_widths(total_stat)
+  %i[lines words bytes].to_h { |key| [key, total_stat[key].to_s.length] }
 end
 
 def format_result(stats, max_widths, options)
-  %i[lines words bytes].filter_map do |key|
+  result = %i[lines words bytes].filter_map do |key|
     stats[key].to_s.rjust(max_widths[key]) if options[key]
   end
-end
-
-def print_stats(stats, max_widths, options)
-  puts (format_result(stats, max_widths, options) << stats[:filename]).join(' ')
+  result << stats[:filename]
 end
 
 main