demonstrates Net::LDAP#open does not expose bind results

we identified that clients cannot safely rely on
Net::LDAP#get_operation_result when using Net::LDAP#open
because @Result is not set.

As a consequence,clients calling
Net::LDAP#get_operation_result would get the previous
last cached result @Result.

Author: vroldanbet

test/integration/test_return_codes.rb

@@ -4,6 +4,14 @@
 # See: section 12.12 http://www.openldap.org/doc/admin24/overlays.html
 
 class TestReturnCodeIntegration < LDAPIntegrationTestCase
+  def test_open_error
+    @ldap.authenticate "fake", "creds"
+    @ldap.open do
+      result = @ldap.get_operation_result
+      assert_equal Net::LDAP::ResultCodeInvalidCredentials, result.code
+    end
+  end
+
   def test_operations_error
     refute @ldap.search(filter: "cn=operationsError", base: "ou=Retcodes,dc=example,dc=org")
     assert result = @ldap.get_operation_result