using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Linq.Expressions;

using Xunit;

namespace LinqStudy.Test.LinqToObject
{
    /// <summary>
    /// where操作符：过滤查询条件
    /// </summary>
    public class WhereTest
    {
        [Fact]
        public void Where_Test()
        {
            var Persons = new List<Person>()
            {
                new Person(){ Id=1,Name="zhangsan",Age=2},
                new Person(){ Id =2,Name="lishi",Age=33}
            };

            var query = Persons.Where(p => p.Name.StartsWith("zhang"));
            var age = query.FirstOrDefault()?.Age;

            Assert.Equal(2, age);
        }

        [Fact]
        public void Where_Argm_Test()
        {
            List<Person> Persons = null;

            Action act = ()=> { Persons.Where(p => p.Name.StartsWith("zhang")); };

            Assert.Throws<ArgumentNullException>(act);
        }
    }
}