How do I apply unit testing to C# function which requires user input dynamically?

Question

The function below gets input from the user. I need to test this function using Unit Testing. Can anyone tell me how to test this kind of function which require user input dynamically. Thanks

like boundary value analysis ...

numberOfCommands should be (0 <= n <= 100)

public static int Get_Commands()
{
    do
    {
        string noOfCommands = Console.ReadLine().Trim();
        numberOfCommands = int.Parse(noOfCommands);             
    }
    while (numberOfCommands <= 0 || numberOfCommands >= 100);  

    return numberOfCommands;
}

Programmatically hint will be great help!

Answer 1

Create an interface and pass in the interface to receive text. Then, in your unit test, pass in a mock interface that automatically returns some result.

Edit for code details:

public interface IUserInput{
    string GetInput();
}

public static int Get_Commands(IUserInput input){
    do{
       string noOfCommands = input.GetInput();
       // Rest of code here
    }
 }

public class Something : IUserInput{
     public string GetInput(){
           return Console.ReadLine().Trim();
     }
 }

 // Unit Test
 private class FakeUserInput : IUserInput{
      public string GetInput(){
           return "ABC_123";
      }
 }
 public void TestThisCode(){
    GetCommands(new FakeUserInput());
 }