ModuleClass1 { public static String reverse(String initial) { return initial != null ? new StringBuilder(initial).reverse().toString(): ""; } private  ModuleClass1(); static String reverse(String initial);  }
@Test public void reverse() throws Exception { assertEquals("", ModuleClass1.reverse(null)); assertEquals("ab", ModuleClass1.reverse("ba")); assertEquals("12345", ModuleClass1.reverse("54321")); }