更新

LinqStudy.Test/LinqStudy.Test.csproj

@@ -7,6 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="FluentAssertions" Version="5.9.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.2.0" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1">
@@ -19,7 +20,6 @@
     <Folder Include="ExpressionTree\" />
     <Folder Include="LinqBase\" />
     <Folder Include="LinqToDataSet\" />
-    <Folder Include="LinqToObject\" />
     <Folder Include="LinqToSQL\" />
     <Folder Include="LinqToXml\" />
     <Folder Include="Util\" />

LinqStudy.Test/LinqToObject/LinqTest.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Linq;
+using System.Linq.Expressions;
+using FluentAssertions;
+
+using Xunit;
+
+namespace LinqStudy.Test.LinqToObject
+{
+    /// <summary>
+    /// 基本项测试
+    /// 异常、空值等项
+    /// </summary>
+    public class LinqTest
+    {
+        [Fact]
+        public void Null_Test()
+        {
+            List<Person> person = null;
+
+            //对Linq操作符而言，基本上数据源为Null时，将引发异常。
+            Assert.ThrowsAny<ArgumentNullException>(() => 
+            {
+                var query = person.Where(p => p == null);
+            });
+        }
+
+        [Fact]
+        public void Count_0_Test()
+        {
+            List<Person> person = new List<Person>();
+
+            //数据源为没有任何内容项时，即 Count=0，不会引发异常。
+            Action action = () => 
+            {
+                //查不到任何数据，不返回null，而是返回 Count=0的对象。
+                person.Where(p => p == null).ToList();
+            };
+
+            action.Should().NotThrow();
+        }
+    }
+}

LinqStudy.Test/LinqToObject/TakeTest.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Linq;
+using System.Linq.Expressions;
+
+using Xunit;
+
+namespace LinqStudy.Test.LinqToObject
+{
+    public class TakeTest
+    {
+        [Fact]
+        public void TakeWhile_Test()
+        {
+            List<Person> customers = new List<Person> {
+                new Person { Id=1,Name="woody1"},
+                new Person { Id=2,Name="woody2"},
+                new Person { Id=3,Name="woody3"},
+                new Person { Id=4,Name="woody1"}
+            };
+
+            var person = customers.TakeWhile(c => c.Name.StartsWith("woody1"));
+
+            //因为匹配第二项时，结果是False，程序返回，不再进行下次迭代，所以返回集合中只有第一项。
+            Assert.Equal(customers.FindAll(q => q.Id == 1), person);        }
+
+        [Fact]
+        public void Test()
+        {
+            List<Person> customers = new List<Person> {
+                new Person { Id=1,Name="woody1"},
+                new Person { Id=2,Name="woody2"},
+                new Person { Id=3,Name="woody3"},
+                new Person { Id=4,Name="woody1"}
+            };
+
+            var person = customers.TakeWhile(c => c.Name.StartsWith("woody2"));
+
+            //因为匹配第一项时，结果是False，程序直接返回，不再进行下次迭代，所以返回空集合。
+            Assert.Empty(person);
+        }
+    }
+}