System.setProperty("abc.xyz", "789");

        value = "${abc.xyz}";
        assertEquals("789", ResourceUtil.resolve(value));

        value = "${abc}${abc.xyz}";
        assertEquals("123789", ResourceUtil.resolve(value));

        value = "xxx${abc.xyz}zzz";
        assertEquals("xxx789zzz", ResourceUtil.resolve(value));

        value = "${\\$}";
        assertEquals(value, ResourceUtil.resolve(value));

        // Test day overflow (day 8 should be treated as day 1)
        // For same-day rules, it should check the day directly
        assertTrue(rule.isTarget(12, 30, 8)); // Should be treated as day 1 (Sunday)

        // Test with cross-midnight rule
        IntervalRule crossRule = new IntervalRule("22:00", "02:00", "1", 1000); // Sunday only