assertThat --- XUnit改进

厌烦了assert.AreEqal();等等一堆的assert方法了吗? 偶然觅得下面这个奇思妙想
看看下面这个:    
 

assertThat(something, eq( " Hello " ));
assertThat(something, eq( true ));
assertThat(something, isA(Color. class ));
assertThat(something, contains( " World " ));
assertThat(something, same(Food.CHEESE));
assertThat(something, NULL);
assertThat(something, NOT_NULL);

 
第二个参数是一个constraint对象.也就是你对something所要检查的约束.

这个功能实在很cool.

1. 没有了那么多的assert方法,看上去很舒服,也更容易理解.

2. 可以方便的组合约束
     

assertThat(something, not(eq( " Hello " )));
assertThat(something, not(contains( " Cheese " )));

3. 自定义约束.  
  

  assertThat(something, between( 10 ,  20 )); 
         public  Constraint between(final  int  min, final  int  max)  {
           return new Constraint() {  
             public boolean eval(Object object) {
               if (!object instanceof Integer) {
                  return false;
               }
               int value = ((Integer)object).intValue();
               return value > min && value < max;
             }
           }
        }

    
   其实这里面也就是个责任分离的思想.为啥我们想不到? 当然放到Nunit中, 这个constraint可以通过Delegate来实现. 自己模拟了一下NUnit下的实现, 不知有没有更好的实现?

using  System;

namespace  xnUnit
{

    class Constraint
    {
        public delegate bool EvalDelegate(object obj);

        public EvalDelegate EvalHandle; 

        public bool Eval(object obj)
        {
            return EvalHandle(obj);
        }
    }
   
    class Assert
    {
        public static void AssertThat(object obj,Constraint con)
        {
            if (con.Eval(obj))
            {
                Console.WriteLine("Pass");
            }
            else
            {
                Console.WriteLine("Failed!");
            }
        }
    }
}

using  System;


namespace  xnUnit
{
    class Program
    {
        public static Constraint Between(int min, int max)
        {
            Constraint con = new Constraint();
            con.EvalHandle = delegate(object obj)
                            {
                                int value = Convert.ToInt32(obj);
                                return value > min && value < max;
                            };
            return con;
        }

        static void Main(string[] args)
        {
            Assert.AssertThat(3, Between(2, 4));
        }
    }
}