Testing startup fails

Command runner could also be used for application startup fail tests:

CommandResult result = TestSupport.buildCommandRunner(App.class)
        .run("server")

or with the shortcut:

CommandResult result = TestSupport.buildCommandRunner(App.class)
        .runApp()

Important

In case of application successful start, special check would immediately stop it by throwing exception (resulting object would contain it), so such test would never freeze.

Why not run directly?

You can run command directly: new App().run("server") But, if application throws exception in run phase, System.exit(1) would be called:

public abstract class Application<T extends Configuration> {
    ...
    protected void onFatalError(Throwable t) {
        System.exit(1);
    }
}

Commands runner runs commands directly so exit would not be called.