Moq mock 抛出了类型 'System.ArgumentNullException' 的异常

Question

我正在使用 moq framework 处理单元测试用例我们在我们的项目中使用了 StructureMap 和 ObjectFactory 来进行依赖项注入。

但是当我尝试模拟未与 Object FActory 一起使用的接口时

我遇到以下异常

'((MyManager)MyManager)' threw an exception of type 'System.ArgumentNullException'

提供的答案适用于 HomeController.cs 方法，但是 MyManager.TestIdentity() 中的那些方法呢？相应地更新了问题。

HomeController.cs

public class HomeController : BaseController
{
    private IMyManager _myManager;
    public IMyManager MyManager
    {
        get
        {
            return _myManager ?? (new MyManager());
        }
        set { _myManager = value; }
    }

    [HttpPost]
    public async Task<IHttpActionResult> TestMock()
    {           
      var response = await MyManager.TestIdentity("demo");
        if (response != null)
        {

            return Ok(identityResponse);
        }

        throw new ApiException(HttpStatusCode.NotFound, 10001,
            "failed");
    }
}

MyManager.cs

public class MyManager : IMyManager
{
    private IMyRespository _myRepository;

    public IMyRespository MyRespository
    {
        get
        {
            return _myRepository;
        }
        set { _myRepository = value; }
    }

    public async Task<CustomerResponseObject> TestIdentity(string demo)
    {
        var result = await MyRespository.GetRoles("user");
    }
}

现在在单元测试项目中我想模拟方法 MyRespository.GetRoles

[TestMethod]
public async Task CreateIdentityWithNullMag()
{
    try
    {            

  //I tried same mock with MyRespository.GetRoles
    var mockIMyRespository = new Mock<IMyRespository>();
            mockIMyRespository .Setup(p =>p.GetRoles(It.IsAny<string>())).
        ReturnsAsync(new RoleObject()
        {
            Name = "admin"
        });
    ObjectFactory.Inject(mockIMyRespository .Object);    


    var controller = new HomeController();
    //working for TestIdentity , failed for GetRoles , i mean GetRole method does not get Mock it has Null exception :(
    controller.MyManager = mockIMyManager.Object;

    await controller.TestMock(request); 

}

'MyRespository' threw an exception of type 'System.ArgumentNullException'

应该怎么办？成功这个模拟？

Answer 1

因为 HomeController.MyManager 有一个 public setter，我会使用它：

var controller = new HomeController();
mockIMyManager.SetupGet(x=>x.MyRepository).Returns(mockIM‌yRespository.Object)‌;
controller.MyManager = mockIMyManager.Object;
await controller.TestMock(request);

Answer 2

根据您的示例假设以下内容

public interface IMyManager {
    Task<CustomerResponseObject> TestIdentity(string username);
}

public interface IMyRespository {
    Task<RoleObject> GetRole(string username);
}

public class RoleObject {
    public string Name { get; set; }
}

public class CustomerResponseObject {
    public RoleObject Role { get; set; }
}

其中 MyManager 是被测系统

public class MyManager : IMyManager {
    private IMyRespository myRepository;

    public MyManager(IMyRespository myRepository) {
        this.myRepository = myRepository;
    }

    public async Task<CustomerResponseObject> TestIdentity(string username) {
        var role = await myRepository.GetRole(username);

        var result = new CustomerResponseObject {
            Role = role
        };
        return result;
    }
}

这里有一个单元测试要测试TestIdentity

[TestClass]
public class MiscUnitTest {
    [TestMethod]
    public async Task MyManager_TestIdentity_With_User_Should_Return_AdminRole() {
        //Arrange
        string username = "user";
        string expectedRole = "admin";
        var mockIMyRespository = new Mock<IMyRespository>();
        mockIMyRespository.Setup(p => p.GetRole(It.IsAny<string>())).
        ReturnsAsync(new RoleObject() {
            Name = expectedRole
        });

        var sut = new MyManager(mockIMyRespository.Object);

        //Act
        var result = await sut.TestIdentity(username);

        //Assert
        Assert.IsNotNull(result);
        Assert.IsNotNull(result.Role);
        Assert.AreEqual(expectedRole, result.Role.Name);
    }
}

Moq mock 抛出了类型 'System.ArgumentNullException' 的异常

Moq mock threw an exception of type 'System.ArgumentNullException'

c#

unit-testing

moq

mocking