@Test public void testaddFieldToBuffer() throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException { UMLArrows arrows = UMLArrows.getInstance(); Field whitelist = WorkerForArrows.class.getDeclaredField("whitelist"); whitelist.setAccessible(true); ArrayList<String> whitelistv1 = new ArrayList<String>(Arrays.asList("java_lang_Object")); whitelist.set(arrows, whitelistv1); Field fieldbuffer = UMLArrows.class.getDeclaredField("fieldBuffer"); fieldbuffer.setAccessible(true); fieldbuffer.set(arrows, new StringBuffer()); arrows.addFieldToBuffer(Opcodes.ACC_PUBLIC, "test", "Ljava/lang/Object;"); assertEquals("+ test : java_lang_Object\\l", fieldbuffer.get(arrows).toString()); }