public void MessageReturnsPropertyNameCanNotBeNull()
        {
            const string propertyName = "NullPropertyName";
            var sut = new NotNull(propertyName);
            const string expected = propertyName + " can not be null";

            var actual = sut.Message;

            Assert.Equal(expected,actual);
        }
        public void IsOfTypeBrokenRule()
        {
            var sut = new NotNull("test");

            Assert.IsAssignableFrom<BrokenRule>(sut);
        }