如何模拟ControllerContext中的DisplayMode进行单元测试c＃

Question

我想在我的控制器中测试一个动作，该动作使用controllerContext作为参数来生成基于第3部分库＆＃34; Rotativa＆＃34;的pdf文档。
这是动作（函数）的实现：

public ActionResult DetailsPrint(int? id)
{
    var a = new ViewAsPdf();
    a.ViewName = "../Ops/_2A1/Details";
    a.Model =UnitOfWork._2A1s.Get(id.Value);
    var pdfBytes = a.BuildPdf(ControllerContext);

    // return ActionResult
    MemoryStream ms = new MemoryStream(pdfBytes);
    return new FileStreamResult(ms, "application/pdf");

}

以下是我尝试进行单元测试的方法：

• 构造

  public _2A1ControllerTest()
  {
      _mockRepository = new Mock<I2A1Repository>();
      var mockUoW = new Mock<IUnitOfWork>();
      _mockHttpContext = new Mock<HttpContextBase>();
      _mockRequest = new Mock<HttpRequestBase>();
      _mockDisplayModeContext = new Mock<IDisplayMode>();
      mockUoW.SetupGet(u => u._2A1s).Returns(_mockRepository.Object);
      _mockHttpContext.SetupGet(x => x.Request).Returns(_mockRequest.Object);
      _controller = new _2A1Controller(mockUoW.Object);
      _controller.MockCurrentUser("test.admin");
      _controller.ControllerContext = new ControllerContext(_mockHttpContext.Object, new System.Web.Routing.RouteData(), _controller);
  }
  

• 测试功能

  [TestMethod]
  public void DetailsPrint_shouldPrint()
  {
      var result = _controller.DetailsPrint(1) as ActionResult;
      result.Should().BeOfType<ActionResult>();
  }
  

  当我执行测试时，我得到以下错误：

  

测试名称：DetailsPrint_shouldPrint   测试FullName：OPSReviewTest._2A1ControllerTest.DetailsPrint_shouldPrint   测试源：C：\ inetpub \ wwwroot \ OpsReview \ OPSReviewTest \ Controllers \ Api_2A1ControllerTest.cs：第46行   测试结果：失败   测试持续时间：0：04：39,3039007   结果StackTrace：
  在System.Web.WebPages.DisplayModeProvider.GetDisplayMode（HttpContextBase context）      在System.Web.Mvc.ControllerContext.get_DisplayMode（）   结果消息：   测试方法OPSReviewTest._2A1ControllerTest.DetailsPrint_shouldPrint抛出异常：   System.NullReferenceException：未将对象引用设置为对象的实例。

任何帮助或建议，谢谢。

Answer 1

您是否正在尝试对您不拥有的代码进行单元测试？ （羞耻，[贝尔收费]，羞耻......）

如果目标是单独测试控制器操作流程，则建议抽象出第三方PDF生成，以便可以模拟它以便于测试。

public interface IViewAsPdfWrapper {
    string ViewName { get; set; }
    object Model { get; set; }
    byte[] BuildPdf(ControllerContext context);
}

public class ViewAsPdfWrapper : IViewAsPdfWrapper {
    private readonly ViewAsPdf view;
    public ViewAsPdfWrapper() {
        view = new ViewAsPdf();
    }
    public string ViewName { get; set; }
    public object Model { get; set; }
    public byte[] BuildPdf(ControllerContext context) {
        view.ViewName = ViewName;
        view.Model = Model;
        return view.BuildPdf(context);
    }
}

现在可以根据需要将抽象注入到控制器中，以便根据请求操作使用。

public class _2A1Controller : Controller {
    private readonly IUnitOfWork UnitOfWork;
    private readonly IViewAsPdfWrapper viewAsPdf;

    public _2A1Controller(IUnitOfWork uow, IViewAsPdfWrapper viewAsPdf) {
        this.UnitOfWork = uow;
        this.viewAsPdf = viewAsPdf;
    }

    public ActionResult DetailsPrint(int? id) {
        var a = viewAsPdf;
        a.ViewName = "../Ops/_2A1/Details";
        a.Model = UnitOfWork._2A1s.Get(id.Value);
        var pdfBytes = a.BuildPdf(ControllerContext);

        // return ActionResult
        MemoryStream ms = new MemoryStream(pdfBytes);
        return new FileStreamResult(ms, "application/pdf");
    }

}

现在单元测试可以安全地模拟第三方功能

public _2A1ControllerTest() {    
    _mockRepository = new Mock<I2A1Repository>();
    var mockUoW = new Mock<IUnitOfWork>();
    mockUoW.SetupGet(u => u._2A1s).Returns(_mockRepository.Object);

    var mockViewAsPdf = new Mock<IViewAsPdfWrapper>();
    mockViewAsPdf.Setup(m => m.BuildPdf(It.IsAny<ControllerContext>()))
        .Returns(() => new byte[0]);

    _mockRequest = new Mock<HttpRequestBase>();
    _mockHttpContext = new Mock<HttpContextBase>();
    _mockHttpContext.SetupGet(x => x.Request).Returns(_mockRequest.Object);

    _controller = new _2A1Controller(mockUoW.Object, mockViewAsPdf.Object);
    _controller.MockCurrentUser("test.admin");
    _controller.ControllerContext = new ControllerContext(_mockHttpContext.Object, new System.Web.Routing.RouteData(), _controller);

}

假设使用FluentAssertions，测试方法应如下所示（Pun意图:)）

[TestMethod]
public void DetailsPrint_shouldPrint() {
    var result = _controller.DetailsPrint(1) as ActionResult;
    result.Should()
        .NotBeNull()
        .And
        .BeAssignableTo<ActionResult>();
}

最后，不要忘记在生产中注册DI容器的界面及其实现。

Answer 2

您忘记将DsiplayMode属性分配给ControllerContext添加此内容：

_controller.ControllerContext.DisplayMode=_mockDisplayModeContext.Object;