C＃ - 如何测试扩展方法？

Question

我为Person类创建了这个C＃扩展方法：

public static class PersonExtensions {
    public static void Rename(this Person person, String newName) {
        person.Name = newName;
    }
}

我该如何对这种方法进行单元测试？ 我已经尝试过，但PersonAccessor对象无法使用Rename方法。

错误是“找不到重命名的私有访问者”

当我尝试PersonExtensions_Accessor.Rename（somePerson，newName）时，它说“有一些无效的参数”

Answer 1

扩展方法只是语法糖，用于引用静态方法的不同方式。 只需在单元测试中调用PersonExtensions.Rename(...) 。

Answer 2

我认为一个好方法可能是直接测试Person实例中的扩展方法。

考虑到您实现的方法，示例代码将是这样的：

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using PersonExtension; // Don't forget about reference it

namespace UnitTest {
    [TestClass]
    public class UnitTest {
        Person person;
        [TestInitialize]
        public void Init() {
            person = new Person("Person name");
        }

        [TestMethod]
        public void TestRename() {
            Assert.AreEqual("Person name", person.Name);
            person.Rename("New name");
            Assert.AreEqual("New name", person.Name);
        }
    }
}

请记住引用Person和PersonExtension类，并在实用程序类中具有正确的隐藏级别，以便可以访问其方法

Answer 3

这是我的生产代码：

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

namespace ClassLibrary1
{
   public class Person
   {
      public string Name { get; set; }
   }

   public static class PersonExtensions
   {
      public static void Rename(this Person person, String newName)
      {
         person.Name = newName;
      }
   }
}

这是生成的测试的编辑版本：

using ClassLibrary1;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;

namespace TestProject1
{


    /// <summary>
    ///This is a test class for PersonExtensionsTest and is intended
    ///to contain all PersonExtensionsTest Unit Tests
    ///</summary>
   [TestClass()]
   public class PersonExtensionsTest
   {


      private TestContext testContextInstance;

      /// <summary>
      ///Gets or sets the test context which provides
      ///information about and functionality for the current test run.
      ///</summary>
      public TestContext TestContext
      {
         get
         {
            return testContextInstance;
         }
         set
         {
            testContextInstance = value;
         }
      }

      #region Additional test attributes
  // 
  //You can use the following additional attributes as you write your tests:
  //
  //Use ClassInitialize to run code before running the first test in the class
  //[ClassInitialize()]
  //public static void MyClassInitialize(TestContext testContext)
  //{
  //}
  //
  //Use ClassCleanup to run code after all tests in a class have run
  //[ClassCleanup()]
  //public static void MyClassCleanup()
  //{
  //}
  //
  //Use TestInitialize to run code before running each test
  //[TestInitialize()]
  //public void MyTestInitialize()
  //{
  //}
  //
  //Use TestCleanup to run code after each test has run
  //[TestCleanup()]
  //public void MyTestCleanup()
  //{
  //}
  //
  #endregion


      /// <summary>
      ///A test for Rename
      ///</summary>
      [TestMethod()]
      public void RenameTest()
      {
         Person person = new Person(); // TODO: Initialize to an appropriate value
         string newName = string.Empty; // TODO: Initialize to an appropriate value
         PersonExtensions.Rename(person, newName); // this could also be written as person.Rename(newName);
         Assert.AreEqual(person.Name, string.Empty);
      }
   }
}

测试通过。