io.c: opening external command

* io.c (rb_io_open_generic): when external command will be invoked
  as other than IO singleton method, probably unintentionally,
  warn if it is File or raise ArgumentError.

From: Nobuyoshi Nakada <nobu@ruby-lang.org>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61317 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 9 insertions, 0 deletions

diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index 00369365d0..89c68b6cb2 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -2184,6 +2184,15 @@ class TestIO < Test::Unit::TestCase
     end
   end
 
+  def test_read_command
+    assert_warn(/invoke external command/) do
+      File.read("|#{EnvUtil.rubybin} -e puts")
+    end
+    assert_raise_with_message(ArgumentError, /invoke external command/) do
+      Class.new(IO).read("|#{EnvUtil.rubybin} -e puts")
+    end
+  end
+
   def test_reopen
     make_tempfile {|t|
       open(__FILE__) do |f|