使用 Nunit 进行单元测试会出错

Question

我刚开始在我的 WebApi 项目中使用 Nunit 进行单元测试。

我为我的控制器开发了一个测试用例：

private readonly INewsBusinessLogic _newsBusinessLogic;

[Test] 
public async Task GetAllNews()
{
   // Arrange
   var controller = new NewsController(_newsBusinessLogic);

   controller.Configuration = new System.Web.Http.HttpConfiguration();
   controller.Request = new System.Net.Http.HttpRequestMessage();

    // Act
    var actionResult = await controller.Get(); 

   //assert
   Assert.IsNotNull(actionResult);
}

API 控制器：

public class NewsController : ApiController 
{  
    private readonly INewsBusinessLogic _newsBusinessLogic;

    public NewsController(INewsBusinessLogic newsBusinessLogic)
    {
        _newsBusinessLogic = newsBusinessLogic;
    }

    public async Task<IHttpActionResult> Get()
    {
       return Ok(await _newsBusinessLogic.GetNewsUpdates());
    }
}

当我调试我的测试时，它在 Act 上给了我一个 NullReferenceException 的错误，我非常清楚 What is a NullReferenceException?。但无法弄清楚，为什么会发生这种情况以及如何解决它。

旁注：我没有使用任何 ORM。

Answer 1

首先，您将null 变量传递给NewsController 构造函数，因为您没有在示例中显示将值分配给_newsBusinessLogic

这是一个使用Moq 的示例，说明如何模拟控制器的依赖项

[Test] 
public async Task GetAllNews()
{
   // Arrange
   var newsBusinessLogicMock = new Mock<INewsBusinessLogic>();
   newsBusinessLogicMock
      .Setup(m => m.GetNewsUpdates())
      .ReturnsAsync("{your desired return here}");

   var controller = new NewsController(newsBusinessLogicMock.Object);

   controller.Configuration = new System.Web.Http.HttpConfiguration();
   controller.Request = new System.Net.Http.HttpRequestMessage();

    // Act
    var actionResult = await controller.Get(); 

   //assert
   Assert.IsNotNull(actionResult);
}