如何对返回 ToList 的操作进行单元测试

Question

Hello I'm trying to run some tests for this Controller Method but I'm struggling to test the View, here's my controller class.

public class StockController : Controller
{
    private readonly IStockService _stockService;

    public StockController(IStockService stockService)
    {
        _stockService = stockService;
    }

    // GET: Stock
    public async Task<IActionResult> Index()
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        IEnumerable<StockDto> stocks = null;
        try
        {
            stocks = await _stockService.GetStockAsync();
        }
        catch (HttpRequestException)
        {
            stocks = Array.Empty<StockDto>();
        }
        return View(stocks.ToList());
    }
}

Here is the Test Method on the MS Test Project for the Stock Controller, I've got the Arrange and Act working fine, but for the Asserts there is a red line on the 'ViewResult' and I'm not sure why.

[TestMethod]
public async Task ReturnIndexMethod()
{
    //Arrange
    var controller = new StockController(new FakeStockService());
    //Act
    var result = await controller.Index(); 
    //Assert
    Assert.IsNotNull(result);
    var AResult = result as ViewResult;
    Assert.IsNotNull(AResult);
    var stockResult = AResult.Value as IEnumerable<StockDto>;
    Assert.IsNotNull(stockResult);

}

Also here is the FakeStockService that will supply mock test Data just in case people need to see it.

public class FakeStockService : IStockService
{
    private readonly IEnumerable<StockDto> _stock = new List<StockDto>
    {
        new StockDto { Id = 1, Name = "asfdaf", Description = "afsdfsfdsda", Price = 5000 }
    };

    public Task<IEnumerable<StockDto>> GetStockAsync()
    {
        return Task.FromResult(_stock);
    }
}

Any help or suggestions would be appreciated, I've just come at a loss here after trying everything else.

Answer 1

Maybe the test is missing the namespace in order to access that ViewResult type.

using Microsoft.AspNetCore.Mvc;
//...

Also, unless that is a typo, the view result should have a Model property, not Value like you have there.

[TestMethod]
public async Task ReturnIndexMethod()
{
    //Arrange
    var controller = new StockController(new FakeStockService());

    //Act
    var result = await controller.Index(); 

    //Assert
    Assert.IsNotNull(result);
    var view = result as ViewResult;
    Assert.IsNotNull(view);
    var stockResult = view.Model as IEnumerable<StockDto>;
    Assert.IsNotNull(stockResult);
}

Everything else in the test looks fine to me.

The controller action however appears to be accessing model state on a GET request. The current example shown does not any obvious need to use the model state so I would suggest removing that

public async Task<IActionResult> Index() {
    IEnumerable<StockDto> stocks = null;
    try {
        stocks = await _stockService.GetStockAsync();
    }
    catch (HttpRequestException) {
        stocks = Array.Empty<StockDto>();
    }
    return View(stocks.ToList());
}