Egge at 02:33, 1 October 2007

2007-10-01T02:33:28Z

← Older revision		Revision as of 02:33, 1 October 2007
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	</pre>		</pre>

			[[Category:Java]]

Brianegge at 03:19, 20 March 2007

2007-03-20T03:19:19Z

New page

One might assume that testing a console app method which calls System.exit() would be impossible to do. By creating a SecurityManager we can detect and defer this call.

<pre>
import java.io.IOException;
import java.security.Permission;
import java.util.Stack;

public class ConsoleAppUnitTest extends UnitTestCase {
private SecurityManager existingSecurityManager;

@Override
protected void setUp() throws Exception {
existingSecurityManager = System.getSecurityManager();
}

@Override
protected void tearDown() throws Exception {
System.setSecurityManager(existingSecurityManager);
}

private static class ExitCatchingSecurityManager extends SecurityManager {
private Stack<Integer> exitCodes = new Stack<Integer>();

public void checkExit(int status) {
exitCodes.push(status);
throw new SecurityException();
}

/**
* This method is called before the original security manager can be replaced. If this method does
* not throw and exception then 'System.setSecurityManager(existingSecurityManager)' will work.
* @param perm anything
*/
@Override
public void checkPermission(Permission perm) {
}

public int getLastExit() {
return exitCodes.pop();
}
}

public void testNoArgsExitsWithReturnCode() {
ExitCatchingSecurityManager securityManager = new ExitCatchingSecurityManager();
try {
System.setSecurityManager(securityManager);
ConsoleApp.main(new String[] { });
fail();
} catch (SecurityException e) {
pass();
assertEquals(2, securityManager.getLastExit());
assertEquals(1, securityManager.getLastExit());
}
}
}
</pre>

System.exit is called twice in this case, because the first System.exit throws an SecurityException which is caught in the 'catch Throwable' line. This trys to call System.exit again, and ends up throwing another exception.
<pre>
@SuppressWarnings({ "CallToSystemExit" })
public static void main(String[] args) {
try {
if (args.length != 2) {
System.err.println("Usage: inputFile outputFile");
System.exit(1);
}
new ConsoleApp(args[0], args[1]).run();
} catch (Throwable t) {
t.printStackTrace(System.err);
System.exit(2);
}
}
</pre>

How to test System.exit - Revision history

Egge at 02:33, 1 October 2007

Brianegge at 03:19, 20 March 2007