Add comments to notify files are auto generated.

tasks/mrbgems_test.rake

@@ -10,6 +10,13 @@ MRuby.each_target do
           File.expand_path(g.test_preload, dir)
         }.find {|file| File.exist?(file) }
 
+        f.puts %Q[/*]
+        f.puts %Q[ * This file contains a test code for #{g.name} gem.]
+        f.puts %Q[ *]
+        f.puts %Q[ * IMPORTANT:]
+        f.puts %Q[ *   This file was generated!]
+        f.puts %Q[ *   All manual changes will get lost.]
+        f.puts %Q[ */]
         if test_preload.nil?
           f.puts %Q[extern const uint8_t mrbtest_assert_irep[];]
         else

test/mrbtest.rake

@@ -41,6 +41,15 @@ MRuby.each_target do
     _pp "GEN", "*.rb", "#{clib.relative_path}"
     FileUtils.mkdir_p File.dirname(clib)
     open(clib, 'w') do |f|
+      f.puts %Q[/*]
+      f.puts %Q[ * This file contains a list of all]
+      f.puts %Q[ * test functions.]
+      f.puts %Q[ *]
+      f.puts %Q[ * IMPORTANT:]
+      f.puts %Q[ *   This file was generated!]
+      f.puts %Q[ *   All manual changes will get lost.]
+      f.puts %Q[ */]
+      f.puts %Q[]
       f.puts IO.read(init)
       mrbc.run f, mrbs, 'mrbtest_irep'
       gems.each do |g|