如何在单元测试中模拟依赖注入对象

Question

My project requires unit testing. I am using constructor dependency injection in my controller. When I mock the injected dependency object in my unit testing project and call it in a test method. Returns null in all cases.

Controller Class:

public class Owner:Controller
{
    private readonly IComRepository repository;
    private readonly DbContext context;
    
    public Owner(IComRepository repository, DbContext context)
    {
      this.repository=repository;
      this.context=context;
    }

    [HttpGet("GetAllTypes")]
    public async Task<IActionResult> GetAllTypes()
    {
      var ownerTypes=repository.GetTypes();
        return Ok(ownerTypes);
    }
}

My Repository Class

public Interface IComRepository
{
    IList<Type> GetTypes();
}
        
public Class ComRepository : IComRepository
{
    private readonly DbContext context;
    public ComRepository(DbContext context)
    {
        this.context=context;
    }
    public IList<Type> GetTypes()
    {
        var allTypes= context.Types.ToList();
        return allTypes;
    }
}

Now I need to test the GetAllTypes methods in my controller class. My Test Class is below mentioned:

using moq;
[TestClass]
public Class OwnerTest
{
    public OwnerTest()
    {
        var mockIcomrepo = new Mock<IComRepository>();
        var mockDbcontext = new Mock<Dbcontext>();
        OwnerController owner = new OwnerController(mockDbContext.Object, mockIcomrepo.Object);
    
    }
    [TestMethod]
    public void GetTypes()
    {
        var allTypes= owner.GetAllTypes(); //It's not trigger to my controller
        Assert.AreEqual(5,allTypes.count());
    }
}

How can I do it? Any one know the answer for this question.

Answer 1

As @Nkosi mentioned you have to use moq setup. Define your mocks outside constructor and initalize them in test class's constructor.

using moq;
[TestClass]
public Class OwnerTest
{
    private readonly IComRepository _mockRepository;
    private readonly OwnerControler _ownerController;
    
    //your mock data
    private readonly IList<Type> mockData; 

    public OwnerTest()
    {
        _mockRepository= new Mock<IComRepository>();

        _ownerController = new OwnerController(mockDbContext.Object, mockIcomrepo.Object);
        mockData=new IList<Type>{"Data1","Data2","Data3","Data4","Data5"};

    }
    
    //choose better names for testing a method 
    //Naming convention like this MethodName_StateUnderTest_ExpectedResult;
    
    [TestMethod]
    public void GetAllTypes() 
    {
        _mockRepository.Setup(p=>p.GetAllTypes()).Returns(mockData);

        var result= _ownerController.GetAllTypes();
        var okResult=Assert.IsType<OkObjectResult>(result)
        var returnTypes=Assert.IsAssignableFrom<IList<Type>>(okResult.Value);
        Assert.AreEqual(5,returnTypes.count());
    }
}

Also, why you inject your dbcontext to controller?your repository should depend dbcontext not controller.