public void IsValid()
 {
     var v = new IPAddressAttribute();
     Assert.IsTrue(v.IsValid("192.168.0.1", null));
     Assert.IsTrue(v.IsValid("255.255.255.255", null));
     Assert.IsTrue(v.IsValid("192.168.0.0", null));
     Assert.IsTrue(v.IsValid(null, null));
     Assert.IsTrue(v.IsValid(IPAddress.Parse("143.24.20.36"), null));
     Assert.IsFalse(v.IsValid("", null));
     Assert.IsFalse(v.IsValid("aaa.bbb.ccc", null));
     Assert.IsFalse(v.IsValid("260.255.255.255", null));
     Assert.IsFalse(v.IsValid("192.999.0.0", null));
 }