fix "ruby -w" warnings

lib/cmdtest/argumentparser.rb

@@ -246,7 +246,7 @@ module Cmdtest
                     end
 
                     # --foo
-                elsif _arg() =~ /^(--\w[-_\w_]*)$/
+                elsif _arg() =~ /^(--\w[-\w]*)$/
                     option = _find_option($1)
                     if option._with_arg()
                         option._set(_arg(1), @opts)
@@ -257,7 +257,7 @@ module Cmdtest
                     end
 
                     # --foo=...
-                elsif _arg() =~ /^(--\w[-_\w]*)=(.*)$/
+                elsif _arg() =~ /^(--\w[-\w]*)=(.*)$/
                     option = _find_option($1)
                     if option._with_arg()
                         option._set($2, @opts)

lib/cmdtest/fssnapshot.rb

@@ -45,7 +45,6 @@ module Cmdtest
       @dir = dir
       @ignored_files = ignored_files
       @fileinfo_by_path = {}
-      dir_prefix = @dir + "/"
       relative_find(@dir) do |path|
         next if path == "."
         file_info = FileInfo.new(path, @dir)

lib/cmdtest/testcase.rb

@@ -63,7 +63,7 @@ module Cmdtest
 
     ORIG_CWD = Dir.pwd
 
-    attr_reader :_work_dir, :_cwd, :_env
+    attr_reader :_work_dir, :_env
 
     def initialize(test_method, clog, runner)
       @_test_method = test_method

lib/cmdtest/workdir.rb

@@ -159,7 +159,7 @@ module Cmdtest
         _quote(_tmp_redirect_sh),
       ]
       before = _take_snapshot
-      ok = system(str)
+      system(str) # TODO: really ignore exit status !?
       after = _take_snapshot
       CmdEffects.new($?,
                      File.read(_tmp_stdout_log),