FallbackProvider is not called.

[OrionRiftStudios]

Hello.
First of all thank you for this amazing framework.

I have a question. (Maybe this is a bug)

I'm using FallBackProvider to inject some services I need in my razor component.

If I use

TestContext.Services.GetService the FallBackProvider is executed as expected.

If I use

TestContext.RenderComponent<mycomponent> my component has some services that must be resolved by the FallBackProvider.

The FallBackProvider is never called.

I think this is a potential bug.

Do you know how to solve this issue ?

Here is the code I am using :

I am trying to load all the services I need for running my integration tests

public class ViewTestBase : TestBase
{
    protected Bunit.TestContext? ctx;

    public ViewTestBase()
    {
    }

    public override async Task Setup()
    {
        await base.Setup();
        ctx = new Bunit.TestContext();
        var scope = Host.Services.CreateScope();

        ctx.Services.AddFallbackServiceProvider(scope.ServiceProvider);
        ctx.Services
          .AddViews();
    }

    public override void ConfigureServices(IServiceCollection services, IConfigurationRoot config1)
    {
        base.ConfigureServices(services, config1);
        services
        .AddApplication()
        .AddFrameworkUI()
        .AddViewModels();
    }
}

The idea is TestBase is building the host and running the TestServer BUnit will load the views and find the missing services from the Host I am using Constructor Injection for the Views replacing the IComponentActivator in my application(normal execution) this is working fine I am using this library
https://github.com/TanvirArjel/TanvirArjel.Blazor
BUnit successfully can load the View but cannot inject the services in the constructor the exception is IViewModel cannot be injected because the concrete class was not found.

but if I use ctx.Services.GetService it works.

this is the Test Class

[Test]
    public void Test()
    {
        // this is working
        var myViewModel = ctx.Services.GetService<IAddEditTradeAccountModalViewModel>();

        // this is not working
        ctx.RenderComponent<TradingRecords>();

        Assert.Pass();
    } 

Thank you

[egil]

Hi there,

It's certainly not expected. Can you share the test (and setup plus relevant fallback service provider) code and the component?

Otherwise it's hard to help. Ideally share a minimal example, e.g. an empty component with just the @inject statement.

[linkdotnet]

I just tried to reproduce the issue and at least on my end with a minimal setup ,everything works as expected:

public class FallbackServiceRendererTest : TestContext
{
    [Fact]
    public void HuppsyWuppsyNoThrowyOwy()
    {
        var servicesCollection = new ServiceCollection();
        servicesCollection.AddScoped<IService>(_ => new NoopService());
        Services.AddFallbackServiceProvider(servicesCollection.BuildServiceProvider());
        Services.GetService<IService>().ShouldBeOfType<NoopService>();

        Action act = () => RenderComponent<ComponentWithFallback>();
        
        act.ShouldNotThrow();
    }

    private class ComponentWithFallback : ComponentBase
    {
        [Inject] IService Service { get; set; }

        protected override void OnInitialized()
        {
            Service.Noop();
        }
    }

    private interface IService
    {
        public void Noop();
    }
    
    private class NoopService : IService
    {
        public void Noop() { }
    }
}

[OrionRiftStudios]

Thank you for your response I updated my original post.

[linkdotnet]

I have a hunch what is causing this issue and it seems more related to the library you are using, but it is hard to tell because I don‘t have all information… like your real component or what your TestBase really does.
Anyway lets try to sort it out.

I found this in the library you are using: AddComponents. I am pretty certain you are using this somewhere in your production code. But you never register that in your test code. Therefore bUnit or better Blazor uses it‘s default way of resolving dependencies, via the Inject Attribute.

So first thing you can do is add the AddComponents but be aware that you have to provide your production assembly as parameter otherwise that library will try to find every IComponent in your test assembly and it will still fail.

Also you can make an easy test:
Refactor your component to use the InjectAttribute instead of ctor dependencies. If it is working we can rule out that bUnit is doing something wrong.

If you have questions let me know.

[OrionRiftStudios]

Thank you I changed the injection in my view using [Inject] attribute with this change now is working.

[linkdotnet]

Okay. Then as I thought. You have to call AddComponents also in your setup with your production assembly to make it work.