public void AddElementsToList_IfListGeneratedIsNull_ReturnsEmptyList()
        {
            //Arrange
            _someFunctions.GenerateList().Returns((List <int>)null); //Mocking dependency class to return a null object (requiers you to specify the type of return object)

            //Action
            var result = sut.AddElementsToList();

            Assert.NotNull(result);
            Assert.Empty(result);
        }
        /// <summary>
        /// Adds additional element to list
        /// </summary>
        /// <returns></returns>
        public List <int> AddElementsToList()
        {
            var list = _someFunctions.GenerateList();

            if (list == null)
            {
                return(new List <int>());
            }
            list.AddRange(Enumerable.Range(1, 5));
            return(list);
        }