Forgot to commit the test part.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@34289 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/test_shellwords.rb

@@ -47,6 +47,11 @@ class TestShellwords < Test::Unit::TestCase
     assert_equal [expected], shellwords(cmdline)
   end
 
+  def test_stringification
+    assert_equal "3", shellescape(3)
+    assert_equal "ps -p #{$$}", ['ps', '-p', $$].shelljoin
+  end
+
   def test_multibyte_characters
     # This is not a spec.  It describes the current behavior which may
     # be changed in future.  There would be no multibyte character