How to add a reference and how to test if is it palindrom using unit test

Question

Firstly I have problem with Visual Studio I cann't add a reference. It says unable to add a reference to project ...

My second question is the testing, i'm not to testing, so could I know the difference between unit test and xunit test, I've seen a xunit is a NuGet package. And I'm not sure If I'm testing right if it's a palindrome.

I've tried to set my Framework to 4.0 I've seen it on SO, so I can add a reference but it didn't work.

namespace PalindromeTest
{
    [TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void IsItPalindrom()
        {
            string a = "1221";
            string b = "1221";
            string res = "";
            if (a == b)
            {
                  res =a;
                  bool x = Program.IsItPalindrom(res);
            }



            Assert.IsTrue(x);
        }
    }
}

My method for testing if the word is palindrome:

 private static bool IsPalindrome(string text)
        {
            int min = 0;
            int max = text.Length - 1;

            while (true)
            {
                if (min > max)
                {
                    return true;
                }

                char a = text[min];
                char b = text[max];

                if (char.ToLower(a) != char.ToLower(b))
                {
                    return false;
                }

                min++;
                max--;
            }

When I run the test or all the test I should see tick on the test explorer, but since I can't add a reference it says that program doesnt contain a definition for IsItPalindrom.

Answer 1

A Windows Universal test project cannot reference a .NET Framework assembly. When you create the test project you should choose the Unit Test Project (.NET Framework) template under Visual C#->Test provided tghat your WPF application or class library targets the .NET Framework.

And xUnit has nothing to do with this.

Answer 2

Your projects are incompatible with each other. If your main project's target is netcoreapp -> than your test projects should be netcoreapp.

If your main project's target is netframework -> than your test projects should be netframework too.

But you can add a reference to netstandard library from any of .NET Frameworks