using System;

using System.Linq;

using System.Collections.Generic;

​

using JerryUnit;

using static JerryUnit.UnitTestAttribute;

public class Program

{

  public static void Main()

  {

    TestRunner.Run(new Custom.MyLibraryTests());

    Console.WriteLine($"{Environment.NewLine}End");

  }

}

​

namespace Custom

{

  public static class MyLibrary

  {

    public static string Reverse(string text)

    {

      if (text is null)

        throw new ArgumentNullException(nameof(text));

      var array = text.ToCharArray();

      Array.Reverse(array);

      return new String(array);

    }

  }

​

  public class MyLibraryTests

  {

    [UnitTest]

    public void Reverse_String_Reversed() =>

        Reverse("Jerry", "yrreJ");

​

    [UnitTest]

    public void Reverse_Empty_Empty() =>

        Reverse(string.Empty, string.Empty);

​

    [UnitTest]

    public void Reverse_Null_ArgumentNullException()

    {

      try { MyLibrary.Reverse(null); }

      catch (ArgumentNullException) { return; }

      Assert(false, "Expected ArgumentNullException");

    }

​

    private static void Reverse(string original, string expected) 

    {

        var actual = MyLibrary.Reverse(original);

        Assert(expected == actual, $"Expected '{expected}' == '{actual}'");

    }

  }  

}

​

namespace JerryUnit

{

  public class UnitTestAttribute : Attribute 

  {

    public static void Assert(bool result, string message = null)

    {

      if (!result) throw new Exception(message);

    }

  }

​

  public static class TestRunner

  {

    public static void Run(object list)

    {

      if (list is null)

        throw new ArgumentNullException(nameof(list));

​

      var tests = FindTests(list);

      if (!tests.Any())

        throw new System.ArgumentException("Test list is empty.");

​

      RunTests(list, tests).ToList().ForEach(x => Console.WriteLine(((x.Success) 

        ? $"✅ Pass: {(list)}.{x.Name}" 

        : $"❌ Fail: {(list)}.{x.Name} > Error: {x.Message}")));

​

      static IEnumerable<System.Reflection.MethodInfo> FindTests(object list) =>

        list.GetType().GetMethods().Where(x => x.GetCustomAttributes(typeof(UnitTestAttribute), false).Any());

​

      static IEnumerable<(bool Success, string Name, string Message)> RunTests(object list, IEnumerable<System.Reflection.MethodInfo> tests) 

      {

        foreach (var test in tests)

        {

          var message = string.Empty;

          try { test.Invoke(list, null); }

          catch (Exception e) { message = (e.InnerException is not null) ? e.InnerException.Message : e.Message; }

          yield return (string.IsNullOrEmpty(message), test.Name, message);

        }

      }

    }

  }

}