public void GetFirstSymbol_GivenNull_StringNullOrEmptyException()
        {
            //Arrange
            string inputString = null;
            // Act
            Action actual = () => GetterFirstSymbol.GetFirstSymbol(inputString);

            // Assert
            Assert.Throws <StringNullOrEmptyException>(actual);
        }
        public void GetFirstSymbol_GivenNotEmptyString_ReturnFirstSymbol(string value, string expected)
        {
            var actual = GetterFirstSymbol.GetFirstSymbol(value);

            Assert.Equal(expected, actual);
        }