public void Equals_operator_should_work_for_inner_list()
        {
            DocumentNumber documentNumber  = "DN/1";
            string         documentNumber2 = "DN/2";

            Assert.False(documentNumber == documentNumber2);
        }
        public void Equals_operator_should_work_for_equal_objects()
        {
            DocumentNumber documentNumber  = "DN/1";
            DocumentNumber documentNumber2 = "DN/1";

            Assert.True(documentNumber == documentNumber2);
        }
        public void Equals_operator_should_work_for_not_equal_object_to_string()
        {
            DocumentNumber documentNumber  = "DN/1";
            string         documentNumber2 = "DN/2";

            Assert.False(documentNumber == documentNumber2);
        }