DefinitionOrderer.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Xunit.Abstractions;
using Xunit.Sdk;

namespace DotNetMVCTest
{
    public class DefinitionOrderer : ITestCaseOrderer
    {
        private readonly IMessageSink diagnosticMessageSink;

        public DefinitionOrderer(IMessageSink diagnosticMessageSink)
        {
            this.diagnosticMessageSink = diagnosticMessageSink;
        }

        public IEnumerable<TTestCase> OrderTestCases<TTestCase>(IEnumerable<TTestCase> testCases)
            where TTestCase : ITestCase
        {
            var result = testCases.ToList();
            var message = new DiagnosticMessage("Ordered {0} test cases", result.Count);
            diagnosticMessageSink.OnMessage(message);
            return result;
        }
    }
}

SampleTests.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Xunit;

[TestCaseOrderer("DotNetMVCTest.DefinitionOrderer", "DotNetMVCTest")]
public class SampleTests
{
    [Fact]
    public void Test2()
    {
        Assert.True(false);
    }

    [Fact]
    public void Test1()
    {
        Assert.True(false);
    }

    [Fact]
    public void YyzTest() {
        Assert.True(false);
    }

    [Fact]
    public void SomethingTest() {
        Assert.True(false);
    }
}