NUnit VS适配器2找不到我的测试

也许有人在Nunit测试中遇到了同样的问题。我已经下载了Nunit和Nunit适配器，我写了一些代码和一些单元测试，但上面写着：

NUnit VS Adapter 2.0.0.0 discovering test is finished
========== Discover test finished: 0 found (0:00:00,4917596) ==========

也许你可以告诉我一些想法，如何解决它？

我读了一些教程，它说我应该使用测试资源管理器，它自动集成了我的测试。但什么都没发生，也许问题在于我使用了3.0.1版本的Nunit？

namespace ConsoleApplication16
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Enter two numbers'n");
            int number1;
            int number2;
            number1 = int.Parse(Console.ReadLine());
            number2 = int.Parse(Console.ReadLine());
            MathsHelper helper = new MathsHelper();
            int x = helper.Add(number1, number2);
            Console.WriteLine("'nThe sum of " + number1 +
                " and " + number2 + " is " + x);
            Console.ReadKey();
            int y = helper.Subtract(number1, number2);
            Console.WriteLine("'nThe difference between " +
                  number1 + " and" + number2 + "  is " + y);
            Console.ReadKey();
        }
    }
    public class MathsHelper
    {
        public MathsHelper() { }
        public int Add(int a, int b)
        {
            int x = a + b;
            return x;
        }
        public int Subtract(int a, int b)
        {
            int x = a - b;
            return x;
        }
    }
}

测试：

using NUnit.Framework;
namespace ConsoleApplication16
{
    [TestFixture]
    public class TestClass
    {
        [TestCase]
        public void AddTest()
        {
            MathsHelper helper = new MathsHelper();
            int result = helper.Add(20, 10);
            Assert.AreEqual(30, result);
        }
        [TestCase]
        public void SubtractTest()
        {
            MathsHelper helper = new MathsHelper();
            int result = helper.Subtract(20, 10);
            Assert.AreEqual(10, result);
        }
    }
}

软件包：

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="NUnit" version="3.0.1" targetFramework="net452" />
  <package id="NUnitTestAdapter" version="2.0.0" targetFramework="net452" />
</packages>

<packages>
  <package id="NUnit" version="3.0.1" targetFramework="net452" />
  <package id="NUnit3TestAdapter" version="3.0.8-ctp-8" targetFramework="net452" />
</packages>