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copied!<p>Indeed, <a href="http://coding.derkeiler.com/Archive/Java/comp.lang.java.programmer/2008-04/msg02603.html" rel="noreferrer">Derkeiler.com</a> suggests:</p> <ul> <li>Why <code>System.exit()</code> ?</li> </ul> <blockquote> <p>Instead of terminating with System.exit(whateverValue), why not throw an unchecked exception? In normal use it will drift all the way out to the JVM's last-ditch catcher and shut your script down (unless you decide to catch it somewhere along the way, which might be useful someday). </p> <p>In the JUnit scenario it will be caught by the JUnit framework, which will report that such-and-such test failed and move smoothly along to the next.</p> </blockquote> <ul> <li>Prevent <code>System.exit()</code> to actually exit the JVM:</li> </ul> <blockquote> <p>Try modifying the TestCase to run with a security manager that prevents calling System.exit, then catch the SecurityException.</p> </blockquote> <pre><code>public class NoExitTestCase extends TestCase { protected static class ExitException extends SecurityException { public final int status; public ExitException(int status) { super("There is no escape!"); this.status = status; } } private static class NoExitSecurityManager extends SecurityManager { @Override public void checkPermission(Permission perm) { // allow anything. } @Override public void checkPermission(Permission perm, Object context) { // allow anything. } @Override public void checkExit(int status) { super.checkExit(status); throw new ExitException(status); } } @Override protected void setUp() throws Exception { super.setUp(); System.setSecurityManager(new NoExitSecurityManager()); } @Override protected void tearDown() throws Exception { System.setSecurityManager(null); // or save and restore original super.tearDown(); } public void testNoExit() throws Exception { System.out.println("Printing works"); } public void testExit() throws Exception { try { System.exit(42); } catch (ExitException e) { assertEquals("Exit status", 42, e.status); } } } </code></pre> <hr> <p>Update December 2012:</p> <p><a href="https://stackoverflow.com/users/557117/will">Will</a> proposes <a href="https://stackoverflow.com/questions/309396/java-how-to-test-methods-that-call-system-exit/309427#comment19186122_309427">in the comments</a> using <a href="http://stefanbirkner.github.com/system-rules/" rel="noreferrer"><strong>System Rules</strong></a>, a collection of JUnit(4.9+) rules for testing code which uses <code>java.lang.System</code>.<br> This was initially mentioned by <strong><a href="https://stackoverflow.com/users/557091/stefan-birkner">Stefan Birkner</a></strong> in <a href="https://stackoverflow.com/a/8658497/6309">his answer</a> in December 2011.</p> <pre><code>System.exit(…) </code></pre> <blockquote> <p>Use the <a href="http://stefanbirkner.github.com/system-rules/#ExpectedSystemExit" rel="noreferrer"><code>ExpectedSystemExit</code></a> rule to verify that <code>System.exit(…)</code> is called.<br> You could verify the exit status, too.</p> </blockquote> <p>For instance:</p> <pre><code>public void MyTest { @Rule public final ExpectedSystemExit exit = ExpectedSystemExit.none(); @Test public void noSystemExit() { //passes } @Test public void systemExitWithArbitraryStatusCode() { exit.expectSystemExit(); System.exit(0); } @Test public void systemExitWithSelectedStatusCode0() { exit.expectSystemExitWithStatus(0); System.exit(0); } } </code></pre>

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