10.1TDD简介

MVC中的测试驱动开发

为什么需要TDD

TDD的由来
它是一种实现代码的方法论而不是一种测试方法



－代码的质量更可靠


TDD的工作方式
－首先编写单元测试
－编写代码用于通过测试
－重构代码
－迭代

编写测试代码
[Test]
public void
StringWithThreeAsReturnsThreeWhenCountingOccurencesOfA() {
//arrange
CharCounter counter = new CharCounter();
//act
int occurrences =
counter.CountOccurrences(“this phrase has three occurrences of a.”, ‘a’);
//assert
Assert.AreEqual(3, occurrences);
}
先写测试

编写应用代码
public int CountOccurrences(string text, char
searchCharacter)
{
int count = 0;
foreach (char character in text) {
if (character == searchCharacter) {
count++;
}}
return count;
}

//代码简单

重构上面的代码
－重构来精简代码

迭代
－重复上面的过程

编写好的单元测试代码
－测试技巧
  1) 不要越界
    －使代码测试工作帮助函数进行定位
   2)默认单元测试
    －自动生成
    ViewData[“Message”] = “Welcome to ASP.NET MVC!”;
return View();
}
public void Index() {
// Arrange
HomeController controller = new HomeController();
// Act
ViewResult result = controller.Index() as ViewResult;
// Assert
ViewDataDictionary viewData = result.ViewData;
Assert.AreEqual(“Welcome to ASP.NET MVC!”, viewData[“Message”]);
}

  3)单元测试要简洁
  －只测试自己写的代码
public ActionResult About()
{
return View();
}
[TestMethod]
public void AboutReturnsAboutView()
{
HomeController controller = new HomeController();
ViewResult result = controller.About() as ViewResult;
Assert.AreEqual(“About”, result.ViewName);
} //不能通过

[TestMethod]
public void AboutReturnsAboutView()
{
HomeController controller = new HomeController();
ViewResult result = controller.About() as ViewResult;
//I explicitly want to rely on the framework to set the viewname
Assert.AreEqual(string.Empty, result.ViewName);
}

只测试自己写的代码

使用TDD的好处
－测试目标明确
－测试文档化
－测试安全
－测试提升质量

TDD推荐参考
－Test Driven Development
－Test-Driven Developmenet in Microsoft.net

2011-4-23 12:14 danny