
using Xunit;
using System;
using System.IO;
using System.Threading.Tasks;

namespace ConsoleApp {
    public class ProgramTests {
        [Fact(DisplayName = "PrintNumbers prints numbers 1 to 5 each on a new line and terminates")] 
        public void PrintNumbers_PrintsNumbersAndTerminates()
        {
            var sw = new StringWriter();
            Console.SetOut(sw);
            Task task = Task.Run(() => Program.PrintNumbers());
            bool finished = task.Wait(1000); // 1 second timeout
            string output = sw.ToString().Trim();
            var lines = output.Split(new[] {'\\n', '\\r'}, StringSplitOptions.RemoveEmptyEntries);

            Assert.True(finished, "Function did not terminate. Possible infinite loop.");
            Assert.Equal(5, lines.Length);
            Assert.Contains("1", lines);
            Assert.Contains("2", lines);
            Assert.Contains("3", lines);
            Assert.Contains("4", lines);
            Assert.Contains("5", lines);
            Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = true });
        }
    }
}

ProgramTests.cs

Deepen your understanding of C# loops with a hands-on, challenge-driven course. Explore for, while, and do-while loops, master nested structures, generate patterns, and tackle real-world problems. Each section alternates between engaging theory and practical coding challenges to ensure you build both conceptual understanding and practical fluency.

Challenge: Detect Infinite Loop

Solution