使用TestServer处理错误情况

Question

I am trying to use TestServer to verify how my application would behave if an exception. For example, in this sample I have a controller will call to a database but in my test I am deliberately setting up the repository to throw an exception.

[Route("api/[controller]")]
public class ValuesController : Controller
{
    private readonly IRepository _repo;

    public ValuesController(IRepository repo)
    {
        _repo = repo;
    }

    // GET api/values
    [HttpGet]
    public IEnumerable<string> Get()
    {
        this._repo.Execute();
        return new string[] { "value1", "value2" };
    }
}

I am expecting an internal server error to be returned. Although this works if were to F5 and run the application I was hoping to do this via TestServer .

    [Fact]
    public void Test1()
    {
        using (var client = new TestServer(new WebHostBuilder()
            .UseStartup<TestStartup>())
            .CreateClient())
        {
            var result = client.GetAsync("api/values").Result;
            Assert.Equal(result.StatusCode, HttpStatusCode.InternalServerError);
        }
    }

    public class TestStartup : Startup
    {
        protected override void ConfigureDependencies(IServiceCollection services)
        {
            services.AddSingleton<IRepository, FailingRepo>();
        }
    }
}

public class FailingRepo : IRepository
{
    public void Execute()
    {
        throw new NotImplementedException();
    }
}

Instead what I get is the test failing for:

System.AggregateException : One or more errors occurred. (The method or operation is not implemented.)

I can get this to work if I was to plug in some custom middleware at the start of the pipeline, something similar to this:

public class ErrorMiddleware
{
    private RequestDelegate next;
    private readonly ILogger logger;

    public ErrorMiddleware(RequestDelegate next, ILogger logger)
    {
        this.next = next;
        this.logger = logger;
    }

    public async Task Invoke(HttpContext context)
    {
        try
        {
            await this.next.Invoke(context);
        }
        catch (Exception e)
        {
            context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
        }
    }
}

I remember being able to do this via Owin Test Server available in the full .NET framework. Any ideas how to go about doing this?

Answer 1

You could use WebApplicationFactory :

public class BasicTests 
    : IClassFixture<WebApplicationFactory<RazorPagesProject.Startup>>
{
    private readonly WebApplicationFactory<RazorPagesProject.Startup> _factory;

    public BasicTests(WebApplicationFactory<RazorPagesProject.Startup> factory)
    {
        _factory = factory;
    }

and instead of the generic type RazorPagesProject.Startup use your own project to test. The factory will provide you the option to access to the routes you want and test they if they are perfoming as you want:

// Arrange
var client = _factory.CreateClient();
// Act
var response = await client.GetAsync("api/Values");
//
response.EnsureSuccessStatusCode(); // Status Code 200-299