Add test on a trx report where the className attribute of TestMethod is missing

This reproduces issue #556

reports/dotnet/DotnetTests.XUnitV3Tests/FixtureTests.cs

@@ -0,0 +1,27 @@
+using System;
+using Xunit;
+
+namespace DotnetTests.XUnitV3Tests;
+
+public sealed class Fixture : IDisposable
+{
+    public void Dispose()
+    {
+        throw new InvalidOperationException("Failure during fixture disposal");
+    }
+}
+
+public class FixtureTests(Fixture fixture) : IClassFixture<Fixture>
+{
+    [Fact]
+    public void Passing_Test()
+    {
+        Assert.NotNull(fixture);
+    }
+
+    [Fact]
+    public void Failing_Test()
+    {
+        Assert.Null(fixture);
+    }
+}