Unit testing using Nunit gives an error

Question

I just started with unit testing using Nunit with my WebApi project.

I've developed one test case for my controller:

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 controller:

public class NewsController : ApiController 
{  
    private readonly INewsBusinessLogic _newsBusinessLogic;

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

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

When I debug my test it gives me an error of NullReferenceException on Act , well I know very well that What is a NullReferenceException?. But cannot figure it out, why this is occurred and how to solve it.

Side Note: I'm not using any ORM.

well for one, you are passing in a `null` variable into `NewsController` constructor as you have not shown in your example where a value is assigned to `_newsBusinessLogic` — Nkosi, Nov 21 '16 at 05:24
You misunderstand. In the test you have not assigned a value to variable, hence why it is null — Nkosi, Nov 21 '16 at 05:30

Nkosi · Accepted Answer · 2016-11-21T05:36:17.177

2

well for one, you are passing in a null variable into NewsController constructor as you have not shown in your example where a value is assigned to _newsBusinessLogic

Here is an example using Moq of how to mock the controller's dependency

[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);
}

edited Nov 21 '16 at 05:36

answered Nov 21 '16 at 05:30

Nkosi

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Thanks!, error gone, but `actionResult` getting null result, can you please tell me the possible cause. – Divyang Desai Nov 21 '16 at 05:58
What did you set for `ReturnsAsync` in the test arrange? – Nkosi Nov 21 '16 at 06:00
I've set `List` like `.ReturnsAsync(new List());` – Divyang Desai Nov 21 '16 at 06:01
Just to confirm. Is `GetNewsUpdates` an async method? – Nkosi Nov 21 '16 at 06:03
Yes, it is. Let me explain a bit more, when i debug its reach to my controller method, but does not reach to the my BL and DAL – Divyang Desai Nov 21 '16 at 06:05
1

Thats because the test is mocking the interface. It will not hit your actual BL and DAL. it a mock. a fake of the intended implementation of the interface. If the goal is to call actual implementations then this unit test turns into an integration test. – Nkosi Nov 21 '16 at 06:07
Alright, thanks for clarification, so now i need to create a separate tests for BL and DAL – Divyang Desai Nov 21 '16 at 06:13

Unit testing using Nunit gives an error

1 Answers1