Using nUnit AND Mstest (Visual Studio Unit Testing) together in perfect harmony

I like mstest. I like the integration. I like right clicking on a method and adding a unit test SNAP done.
It works great for me. nUnit is 'ok' to me. Integration is poor without third party tools. You have to change things around to get it to work. Sometimes I get strange errors I just dont get using mstest.
You have to set config files up to be named the same as the project. Not intuitive at first since nothing actually tells you this - you expect to be able to tell it your assembly and voila. Now.. you can use a different sequence of events to prevent this, such as add assembly before creating a project in nUnit, but thats not obvious to anyone first using it.

however.. to use nUnit on a build server I dont need to install Visual Studio. In order to use Microsoft's unit testing, you need to either install Visual Studio on the build server or go through a hack to get the components on there. Its not pretty. So nUnit shines here. But.. why not use mstest in the IDE and nUnit on your build server? They have different namespaces - but you can change the aliases around to do this successfully.

At the top of your classes in your unit test projects define the following to default to microsoft testing unless a build constant is defined called NUNIT

#if !NUNIT
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Category = Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute;
#else
using NUnit.Framework;
using TestInitialize = NUnit.Framework.SetUpAttribute;
using TestContext = System.Object;
using TestProperty = NUnit.Framework.PropertyAttribute;
using TestClass = NUnit.Framework.TestFixtureAttribute;
using TestMethod = NUnit.Framework.TestAttribute;
using TestCleanup = NUnit.Framework.TearDownAttribute;
#endif

Go into Visual Studio, choose the Build menu and select "Configuration Manager"
Select "new" and name this build Nunit (or mstest or whatever you want to NOT be your debug/release build). Personally.. I use a build name called MsTest since my debug builds are what get automatically tested every night with cruisecontrol.net/nant/nUnit so I want my default builds to compile with nUnit, but when I want to add/debug unit tests in the IDE I simply change my build to MsTest.

Once you create a new build name, go into each of your projects once you select the build, and go to prokect properties. In the Build tab under "Conditional Compilation Symbols" type in MSTEST or NUNIT.
Use NUNIT if you call your build nUnit and use the code above. This will assume you want your default debug/release build to default to Microsoft. Case DOES matter for the conditional compilation constants.. make sure you use all uppercase.. its easier.

If you want to create a separate build configuration for testing Microsoft unit tets, but want to keep the default debug/release for nUnit then your headers would look like this:

#if MSTEST
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Category = Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute;
#else
using NUnit.Framework;
using TestInitialize = NUnit.Framework.SetUpAttribute;
using TestContext = System.Object;
using TestProperty = NUnit.Framework.PropertyAttribute;
using TestClass = NUnit.Framework.TestFixtureAttribute;
using TestMethod = NUnit.Framework.TestAttribute;
using TestCleanup = NUnit.Framework.TearDownAttribute;
#endif

hope this helps : )