Capture the result of stderr to check the warning message.

Author: satoryu

test/test_ldap_connection.rb

@@ -1,6 +1,14 @@
 require_relative 'test_helper'
 
 class TestLDAPConnection < Test::Unit::TestCase
+  def capture_stderr
+    stderr, $stderr = $stderr, StringIO.new
+    yield
+    $stderr.string
+  ensure
+    $stderr = stderr
+  end
+
   def test_unresponsive_host
     assert_raise Net::LDAP::Error do
       Net::LDAP::Connection.new(:host => 'test.mocked.com', :port => 636)
@@ -16,9 +24,12 @@ def test_blocked_port
 
   def test_connection_refused
     flexmock(TCPSocket).should_receive(:new).and_raise(Errno::ECONNREFUSED)
-    assert_raise Net::LDAP::ConnectionRefusedError do
-      Net::LDAP::Connection.new(:host => 'test.mocked.com', :port => 636)
+    stderr = capture_stderr do
+      assert_raise Net::LDAP::ConnectionRefusedError do
+        Net::LDAP::Connection.new(:host => 'test.mocked.com', :port => 636)
+      end
     end
+    assert_equal("Deprecation warning: Net::LDAP::ConnectionRefused will be deprecated. Use Errno::ECONNREFUSED instead.\n",  stderr)
   end
 
   def test_raises_unknown_exceptions