Code Recipe: How to generate random alpha numeric string in C# .Net

This C# .Net code is from the Code Recipes series of Test Automation TV YouTube Channel.
The full explanation of the code is available in the video.

public string GenerateRandomString(int stringLength = 10)
        {
            if(stringLength < 1)
            {
                stringLength = 10;
            }

            StringBuilder retVal = new StringBuilder();

            Random rNumberSmallCapsOrSpecialChar = new Random(DateTime.Now.Millisecond);

            int typeOfCharToGenerate = 1;

            for (int i = 0; i < stringLength; i++)
            {
                typeOfCharToGenerate = rNumberSmallCapsOrSpecialChar.Next(1, 4);

                switch (typeOfCharToGenerate)
                {
                    case 1:// generate a number
                        retVal.Append(rNumberSmallCapsOrSpecialChar.Next(0, 9));
                        break;
                    case 2: // generate a small alphabet
                        retVal.Append((char)rNumberSmallCapsOrSpecialChar.Next(97, 122));
                        break;
                    case 3: // generate a capital alphabet
                        retVal.Append((char)rNumberSmallCapsOrSpecialChar.Next(65, 90));
                        break;
                    case 4: // special char
                        retVal.Append((char)rNumberSmallCapsOrSpecialChar.Next(33, 46));
                        break;
                }
            }

            return retVal.ToString();
        }

  [TestMethod]
        public void MakeRandomString()
        {
            for (int i = 0; i < 10; i++)
            {
                Console.WriteLine(GenerateRandomString());
                System.Threading.Thread.Sleep(10);
            }
        }

This video also shows how to use Visual Studio 2019 test explorer to run tests.
Other topics included are

1. typecasting of an int to a char in C#
2. Using StringBuild.Append method
3. Using Random class and Next method
4. Specifying default parameter values in methods
5. Using Sleep method call

Visual Studio 2019 New Features

Visual Studio 2019 is  geared towards making developers more productive, and innovative. 

It introduces live code sharing, time travel debugging, data breakpoints, C++ low memory foot print, improved VS on Mac, improved power shortcut keys, and much.