如何在c#中对这个方法进行单元测试？

Question

我正在学习单元测试.如何使用nunit和rhino mock对这个方法进行单元测试？

public ActionResult PrintCSV(Byte[] bytes, string fileName)
{
    var file = File(bytes, "application/vnd.ms-excel");
    var cd = new System.Net.Mime.ContentDisposition()
    {
        CreationDate = DateTime.Now,
        FileName = fileName,
        Inline = false
    };
    Response.AppendHeader("Content-Disposition", cd.ToString());
    return file;
}

Answer 1

您将需要模拟HttpContext.这是一个例子(它是MSTest但是我觉得移植到NUnit并不是很痛苦 - 你需要的只是重命名一些属性):

[TestMethod]
public void PrintCSV_Should_Stream_The_Bytes_Argument_For_Download()
{
    // arrange 
    var sut = new HomeController();
    var bytes = new byte[] { 1, 2, 3 };
    var fileName = "foobar";
    var httpContext = MockRepository.GenerateMock<HttpContextBase>();
    var response = MockRepository.GenerateMock<HttpResponseBase>();
    httpContext.Expect(x => x.Response).Return(response);
    var requestContext = new RequestContext(httpContext, new RouteData());
    sut.ControllerContext = new ControllerContext(requestContext, sut);

    // act
    var actual = sut.PrintCSV(bytes, fileName);

    // assert
    Assert.IsInstanceOfType(actual, typeof(FileContentResult));
    var file = (FileContentResult)actual;
    Assert.AreEqual(bytes, file.FileContents);
    Assert.AreEqual("application/vnd.ms-excel", file.ContentType);
    response.AssertWasCalled(
        x => x.AppendHeader(
            Arg<string>.Is.Equal("Content-Disposition"),
            Arg<string>.Matches(cd => cd.Contains("attachment;") && cd.Contains("filename=" + fileName))
        )
    );
}

正如您所看到的,这里有一些管道代码来设置测试.我个人使用MvcContrib.TestHelper,因为它简化了很多这个管道代码,使测试更具可读性.看一下这个:

[TestClass]
public class HomeControllerTests : TestControllerBuilder
{
    private HomeController sut;

    [TestInitialize]
    public void TestInitialize()
    {
        this.sut = new HomeController();
        this.InitializeController(this.sut);
    }

    [TestMethod]
    public void PrintCSV_Should_Stream_The_Bytes_Argument_For_Download()
    {
        // arrange 
        var bytes = new byte[] { 1, 2, 3 };
        var fileName = "foobar";

        // act
        var actual = sut.PrintCSV(bytes, fileName);

        // assert
        var file = actual.AssertResultIs<FileContentResult>();
        Assert.AreEqual(bytes, file.FileContents);
        Assert.AreEqual("application/vnd.ms-excel", file.ContentType);
        this.HttpContext.Response.AssertWasCalled(
            x => x.AppendHeader(
                Arg<string>.Is.Equal("Content-Disposition"),
                Arg<string>.Matches(cd => cd.Contains("attachment;") && cd.Contains("filename=" + fileName))
            )
        );
    }
}

现在测试更加清晰,因为我们可以立即看到初始化阶段,被测试方法的实际调用和断言.

备注:所有这些都说我不太明白控制器动作的意义,它将一个字节数组作为参数,只是为了将它流回客户端.我的意思是,为了调用它,客户端需要已经拥有该文件,那么重点是什么？但我想这只是为了说明目的.在您的实际方法中,字节数组不作为参数传递,而是从控制器操作中从某些外部依赖项中检索.在这种情况下,您也可以模拟这种依赖关系(假设您当然已经正确地构建了图层,并且它们的耦合程度非常弱).