Switching Between Using NUnit and MSTest for Unit Testing

Question

How can I configure a .NET solution (C#, .NET 2.0) to to allow other developers to make use of the same unit tests for the solution using either NUnit or MSTest?

Background:

In this project, some developers use VS2005 Team Edition, and others make use of VS2005 Pro, so not all of the developers are able to run MSTest. Given that this is an Enterprise project, the team is not able to make use of TestDriven.net or ReSharper. I am aware using either of these products with VS would resolve this issue, but given the time it would take to authorize the purchase of licenses, buying either of these products isn't a viable option.

Thanks in advance for your help, MagicAndi.

Answer 1

The best solution I have found is to make use of a simple piece of code I found in this article. Simply use this code snippet in the namespace section of each .cs test file:

#if NUNIT
using TestClass = NUnit.Framework.TestFixtureAttribute;
using TestMethod = NUnit.Framework.TestAttribute;
using TestCleanup = NUnit.Framework.TearDownAttribute;
using TestInitialize = NUnit.Framework.SetUpAttribute;
using ClassCleanup = NUnit.Framework.TestFixtureTearDownAttribute;
using ClassInitialize = NUnit.Framework.TestFixtureSetUpAttribute;
#else
using Microsoft.VisualStudio.TestTools.UnitTesting;
#endif

using NUnitAssert = NUnit.Framework.Assert;
using MsAssert = Microsoft.VisualStudio.TestTools.UnitTesting.Assert;

The NUNIT in the code snippet refers to a custom build configuration for the solution. You can create this using the VS Configuration Manager (via the VS toolbar or the solution properties). Also, you need to replace all instances of the NUnit's Test attribute on your methods to make use of the MSTest TestMethod attribute (or vice versa).

EDIT: Updated the code snippet above to include a possible fix for the issue Jamie Ide pointed out in the comments. Note, I haven't managed to test this fix. The updated code snippet is taken from a comment by Simon on this blog post.

Answer 2

If you don't want to change any test code (i.e. don't want to add the aliasing at the top), this shim works for me:

using System;
using System.Collections;

namespace Microsoft.VisualStudio.TestTools.UnitTesting
{
    public class Placeholder{}
    public class TestClassAttribute : NUnit.Framework.TestFixtureAttribute
    {
    }
    public class TestInitializeAttribute : NUnit.Framework.SetUpAttribute
    {
    }
    public class TestMethodAttribute : NUnit.Framework.TestAttribute
    {
    }
    public class TestCleanupAttribute : NUnit.Framework.TearDownAttribute
    {
    }
    public class IgnoreAttribute : NUnit.Framework.IgnoreAttribute
    {
    }
    public class ExpectedExceptionAttribute : NUnit.Framework.ExpectedExceptionAttribute
    {
        public ExpectedExceptionAttribute(Type exceptionType) : this(exceptionType, null)
        {
        }
        public ExpectedExceptionAttribute(Type exceptionType, string message) : base(exceptionType)
        {
            UserMessage = message;
        }
    }
    public class TestContext : NUnit.Framework.TestContext
    {
        public TestContext(IDictionary dictionary) : base(dictionary)
        {
        }
    }
    public class Assert : NUnit.Framework.Assert
    {
        public static void IsInstanceOfType(object obj, Type type)
        {
            NUnit.Framework.Assert.IsInstanceOfType (type, obj, null);
        }
        public static void IsInstanceOfType(object obj, Type type, string message)
        {
            NUnit.Framework.Assert.IsInstanceOfType (type, obj, message);
        }
    }
    public class CollectionAssert : NUnit.Framework.CollectionAssert
    {
    }
}

This has worked for me to run MSTest via NUnit (at least under mono with Xamarin Studio). Just include the file and get references right (you may need a different project file or conditional references), and you're good.

Answer 3

Do you have a mix of existing tests? If not, or you don't mind converting existing MSTests, I would standardize on NUnit. I strongly prefer NUnit over MSTest; it's faster and it doesn't force you to have the TestContext nonsense in your test classes. It's also more compatible with CI servers.