Making Nunit tests execute in order

Have you ever wanted to run a given suite of Nunit tests in order? Normally your tests should be created in such a way that execution order is no concern. I stand by that rule, however there is that one edge case were you need to break that rule. The one scenario I came across was with R.NET whereby in a given process you can only initialize one R Engine and once disposed you cannot reinitialize. One of my test happened to deal with disposing the engine and if this test were to run before any other test(s) they would fail.

You will find below a code snippet of how I managed to get this to run in order using Nunit.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using NUnit.Framework;
using RSamples;

    public class OrderedTestAttribute : Attribute
        public int Order { get; set; }

        public OrderedTestAttribute(int order)
            this.Order = order;

    public class TestStructure
        public Action Test;

    public class SampleTests
        public void CleanUpAfterTest()

        public void Test1(){}

        public void Test2(){}

        public void Test3(){}

        [TestCaseSource(sourceName: "TestSource")]
        public void MainTest(TestStructure test)

        public static IEnumerable<TestCaseData> TestSource
                var assembly = Assembly.GetExecutingAssembly();
                Dictionary<int, List<MethodInfo>> methods = assembly
                    .SelectMany(x => x.GetMethods())
                    .Where(y => y.GetCustomAttributes().OfType<OrderedTestAttribute>().Any())
                    .GroupBy(z => z.GetCustomAttribute<OrderedTestAttribute>().Order)
                    .ToDictionary(gdc => gdc.Key, gdc => gdc.ToList());

                foreach (var order in methods.Keys.OrderBy(x => x))
                    foreach (var methodInfo in methods[order])
                        MethodInfo info = methodInfo;
                        yield return new TestCaseData(
                            new TestStructure
                                Test = () =>
                                    object classInstance = Activator.CreateInstance(info.DeclaringType, null);
                                    info.Invoke(classInstance, null);


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s