test/ruby/test_io.rb: new test for IO.select exception set

Ensure this rarely-used feature of IO.select continues
to work properly.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58806 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 12 insertions, 0 deletions

diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index 1b8179b516..ecf5658d22 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -3553,4 +3553,16 @@ __END__
       }
     end if IO.method_defined?(:pread) and IO.method_defined?(:pwrite)
   end
+
+  def test_select_exceptfds
+    TCPServer.open('localhost', 0) do |svr|
+      con = TCPSocket.new('localhost', svr.addr[1])
+      acc = svr.accept
+      assert_equal 6, con.send('hello', Socket::MSG_OOB)
+      set = IO.select(nil, nil, [acc], 30)
+      assert_equal([[], [], [acc]], set, 'IO#select exceptions array OK')
+      acc.close
+      con.close
+    end
+  end if Socket.const_defined?(:MSG_OOB)
 end