Allow tests to System.exit() by default

Otherwise the ApplicationContext stays alive and if it's a
server app the JVM does not exit at the end of "spring test".
User can override with "spring test foo.groovy --nohup"
(which we have to do in our unit tests).

spring-boot-cli/src/test/java/org/springframework/boot/cli/CliTester.java

@@ -75,7 +75,10 @@ public class CliTester implements TestRule {
 	}
 
 	public String test(String... args) throws Exception {
-		Future<TestCommand> future = submitCommand(new TestCommand(), args);
+		String[] argsToUse = new String[args.length + 1];
+		System.arraycopy(args, 0, argsToUse, 1, args.length);
+		argsToUse[0] = "--nohup";
+		Future<TestCommand> future = submitCommand(new TestCommand(), argsToUse);
 		this.commands.add(future.get(this.timeout, TimeUnit.MILLISECONDS));
 		return getOutput();
 	}