reorganize code

Author: swa-ds

src/test/java/de/doubleslash/app/AppTest.java

@@ -9,11 +9,12 @@
 
 public class AppTest {
 
-    private final App app = new App();
-
     @RegisterExtension
     static final AssertLoggedExtension assertLogged = new AssertLoggedExtension();
 
+    // subject under test
+    private final App app = new App();
+
     @Test
     public void shouldHaveLogged() {
         app.run();