同时使用MSTest与NUnit进行单元测试设置

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