VS2010整合NUnit进行单元测试

Calculatornamespace UnitTestApp
{
    public class Calculator
    {
        public int Add(int a, int b)
        {
            return a + b;
        }

        private static readonly object objSync = new object();
        private static Calculator instance = null;

        public static Calculator GetInstance()
        {
            if (instance == null)
            {
                lock (objSync)
                {
                    if (instance == null)
                    {
                        instance = new Calculator();
                    }
                }
            }
            return instance;
        }

    }
}

UnitTestusing NUnit.Framework;

namespace UnitTestApp
{
    [TestFixture]
    public class NUnitTest
    {
        [Test]
        public void AddTest()
        {
            var calc = new Calculator();
            var result = calc.Add(1, 1);
            Assert.AreEqual(2, result);
        }

        [Test]
        public void AddTestFailure()
        {
            var calc = new Calculator();
            var result = calc.Add(1, 1);
            Assert.AreEqual(10, result);
        }

        [Test]
        public void SingtonTest1()
        {
            var calc = Calculator.GetInstance();
            Assert.IsNull(calc);
        }

        [Test]
        public void SingtonTest2()
        {
            var calc1 = Calculator.GetInstance();
            var calc2 = Calculator.GetInstance();
            Assert.IsTrue(object.Equals(calc1, calc2));
        }
    }
}