Refactor C# projects

csharp.NUnit/GildedRoseTests/ApprovalTest.cs

@@ -0,0 +1,24 @@
+using System;
+using System.IO;
+using System.Text;
+using System.Threading.Tasks;
+using NUnit.Framework;
+using VerifyNUnit;
+
+namespace GildedRoseTests;
+
+public class ApprovalTest
+{
+    [Test]
+    public Task ThirtyDays()
+    {
+        var fakeOutput = new StringBuilder();
+        Console.SetOut(new StringWriter(fakeOutput));
+        Console.SetIn(new StringReader($"a{Environment.NewLine}"));
+
+        TextTestFixture.Main(new string[] { "30" });
+        var output = fakeOutput.ToString();
+
+        return Verifier.Verify(output);
+    }
+}