try { ClassUtils.getPackageName((Class) null); fail(); } catch (IllegalArgumentException ex) {}
assertEquals("", ClassUtils.getPackageName((Class)null));
    public void test_getPackageName_Class() {        assertEquals("java.lang", ClassUtils.getPackageName(String.class));        assertEquals("java.util", ClassUtils.getPackageName(Map.Entry.class));        try {            ClassUtils.getPackageName((Class) null);            fail();        } catch (IllegalArgumentException ex) {}    }