How to test executable JAR?

Question

I have a simple class in executable JAR file:

public final class Main {
  public static void main(String[] args) {
    System.out.println("hello, world!");
    System.exit(-1);
  }
}

Now I'm trying to test this class/method:

public class MainTest {
  @Test public void testMain() {
    Main.main(new String[] { "something" });
  }
}

Testing crashes on System.exit(0), and I can understand why. Now what should I do? Shall I mock System? What is a standard approach here? Btw, maybe I should test the method "in container" (read "in JAR"), the same way we're doing it with WAR files?

I changed the question. I'm calling `System.exit(-1)`. This just an example, in my real-life project everything is much more complex, of course — yegor256, Dec 19 '10 at 12:03
Duplicate? http://stackoverflow.com/questions/309396/java-how-to-test-methods-that-call-system-exit — khachik, Dec 19 '10 at 12:47

score 1 · Answer 1 · answered Dec 19 '10 at 12:06

1

Use of AspectJ around advice could possibly work here, as you would be able to intercept the call to System.exit.

answered Dec 19 '10 at 12:06

Noel M

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user85421 · Accepted Answer · 2010-12-19T14:54:46.217

Use a security police or a Security Manager that does not allow the Virtual Machine to be terminated by exit.

    System.setSecurityManager(new SecurityManager() {
        @Override
        public void checkExit(int status) {
            throw new AccessControlException("exit not allowed during testing");
        }
    });

A possible drawback is that a call to exit will throw an Exception,

See java.lang.SecurityManager and Permissions in the JDK for details.

(I do not like the idea of calling exit - kind of a harsh way to stop the Virtual Machine.)

Peter Lawrey · Answer 3 · 2010-12-19T13:00:25.350

0

Your main shouldn't call System.exit(0); if it didn't it would make no difference, except you can call it in a test.

Or you shouldn't test the main, as you don't actually check anything it does.

EDIT: In the past I have gone with the suggestion to use a SecurityManager to prevent System.exit() shutting down the unit test. However, over the last few years I have just made sure not to use System.exit() for many reasons including this one.

edited Dec 19 '10 at 13:00

answered Dec 19 '10 at 11:57

Peter Lawrey

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Pleas, see my comment above and the changes I made to the question – yegor256 Dec 19 '10 at 12:04

How to test executable JAR?

3 Answers3