.net – Switching Between Using NUnit and MSTest for Unit Testing

mstestnetnunitunit testing

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.

Best Answer

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.

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

C# – the difference between const and readonly in C#

Apart from the apparent difference of

having to declare the value at the time of a definition for a const VS readonly values can be computed dynamically but need to be assigned before the constructor exits.. after that it is frozen.
const's are implicitly static. You use a ClassName.ConstantName notation to access them.

There is a subtle difference. Consider a class defined in AssemblyA.

public class Const_V_Readonly
{
  public const int I_CONST_VALUE = 2;
  public readonly int I_RO_VALUE;
  public Const_V_Readonly()
  {
     I_RO_VALUE = 3;
  }
}

AssemblyB references AssemblyA and uses these values in code. When this is compiled:

in the case of the const value, it is like a find-replace. The value 2 is 'baked into' the AssemblyB's IL. This means that if tomorrow I update I_CONST_VALUE to 20, AssemblyB would still have 2 till I recompile it.
in the case of the readonly value, it is like a ref to a memory location. The value is not baked into AssemblyB's IL. This means that if the memory location is updated, AssemblyB gets the new value without recompilation. So if I_RO_VALUE is updated to 30, you only need to build AssemblyA and all clients do not need to be recompiled.

So if you are confident that the value of the constant won't change, use a const.

public const int CM_IN_A_METER = 100;

But if you have a constant that may change (e.g. w.r.t. precision).. or when in doubt, use a readonly.

public readonly float PI = 3.14;

Update: Aku needs to get a mention because he pointed this out first. Also I need to plug where I learned this: Effective C# - Bill Wagner

Best Answer

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