Spring enabled FTP Server NPE on start/stop/start

[Alex Parvulescu]

Hello guys,

I wanted to use FTPServer with Spring, but I have some unit tests
failing. I am using it to unit test a FTP Client connector that I'm
working on.

You only need to start and stop the server a couple of times. Always
the second test fails with a NPE.

This is the unit test file (it is very very basic):

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "/ftpContextTest.xml" })
public class FTPServerSpringTest {

        @Autowired
        private FtpServer ftpServer;

        @Before
        public void before() throws FtpException {
                ftpServer.start();
        }

        @Test
        public void test1() {
                System.out.println("nothing");
        }

        @Test
        public void test2() {
                System.out.println("nothing");
        }

        @After
        public void after() {
                ftpServer.stop();
        }
}


This is the spring config file:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans";
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xmlns:ftpserver="http://mina.apache.org/ftpserver/spring/v1";
        xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
        http://mina.apache.org/ftpserver/spring/v1
http://mina.apache.org/ftpserver/ftpserver-1.0.xsd";>

        <ftpserver:server id="ftpServer" anon-enabled="true">
                <ftpserver:listeners>
                        <ftpserver:nio-listener name="default" port="3333"
                                local-address="localhost" />
                </ftpserver:listeners>
        </ftpserver:server>
</beans>

The stack trace:

java.lang.NullPointerException
        at 
org.apache.ftpserver.impl.DefaultFtpServer.start(DefaultFtpServer.java:74)
        at 
com.pfalabs.ftpserver.FTPServerSpringTest.before(FTPServerSpringTest.java:22)


Digging into this deeper it seems this code will get you the NPE really fast:

ftpServer.start();
ftpServer.stop();
ftpServer.start();

--> java.lang.NullPointerException
        at 
org.apache.ftpserver.impl.DefaultFtpServer.start(DefaultFtpServer.java:74)
        at com.pfalabs.ftpserver.FTPServerTest.test1(FTPServerTest.java:40)



Looking at the code I'm not sure I am supposed to be doing that:
start/stop/start, but this is the way I have my unit tests.
One workaround would be to have a static method to initialize the
FTPServer Component, but that would be ignoring spring altogether.
Or maybe forcing spring to NOT return a singleton each time it will
try to inject the bean can fix this.

This is not a blocking issue for me, Its something I've seen while
trying to take FTPServer for a spin.

thanks,
alex