"Cannot resolve parameter" error in ABP Framework Test

Question

I am trying to write test code:

public class SupplierAppServiceTests : ABCApplicationTestBase
{
    private readonly ISupplierAppService _supplierAppService;
    private readonly IWmsCompanyRepository _fakeRepo;

    public SupplierAppServiceTests()
    {
        _fakeRepo = Substitute.For<IWmsCompanyRepository>();
        _supplierAppService = GetRequiredService<ISupplierAppService>();
    }

    [Fact]
    public async Task Should_Be_Generate_Code()
    {
        // Arrange
        _fakeRepo.CreateAsync(Arg.Any<WmsCompany>())
            .Returns(Task.CompletedTask);
        ...
    }
}

But I get this error:

Autofac.Core.DependencyResolutionException : An exception was thrown while activating MyCompany.ABC.Application.CompanySuppliers.SupplierAppService.
    ---- Autofac.Core.DependencyResolutionException : None of the constructors found with 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder' on type 'MyCompany.ABC.Application.CompanySuppliers.SupplierAppService' can be invoked with the available services and parameters:
    Cannot resolve parameter 'MyCompany.ABC.Domain.Wms.Companies.IWmsCompanyRepository wmsCompanyRepository' of constructor 'Void .ctor(MyCompany.ABC.Domain.Companies.SupplierManager, MyCompany.ABC.Domain.Companies.ISupplierRepository, MyCompany.ABC.Domain.Wms.Companies.IWmsCompanyRepository)'.

WmsCompanyRepository class (last parameter) which implements IWmsCompanyRepository makes a request to 3rd party's webservice.

SupplierAppService:

public class SupplierAppService : ABCAppService, ISupplierAppService
{
    public SupplierAppService(SupplierManager supplierManager, ISupplierRepository supplierRepository, IWmsCompanyRepository wmsCompanyRepository)
    {
        this.supplierManager = supplierManager;
        this.supplierRepository = supplierRepository;
        this.WmsCompanyRepository = wmsCompanyRepository;
    }

    ...
}

IWmsCompanyRepository:

public interface IWmsCompanyRepository
{
     Task CreateAsync(WmsCompany company);
}

I changed _supplierAppService assignment in SupplierAppServiceTests class' constructor

from:

_supplierAppService = GetRequiredService<ISupplierAppService>();

to:

_supplierAppService = new SupplierAppService(_supplierManager, _supplierRepository, _fakeRepo);

SupplierAppService's methods use ObjectMapper property and this time I am getting this error:

ObjectMapper -> System.ArgumentNullException : Value cannot be null. (Parameter 'provider') objectmapper

How can I inject IWmsCompanyRepository to SupplierAppService properly for test case?

Answer 1

Add your _fakeRepo singleton to services so that it can be resolved for SupplierAppService.

public SupplierAppServiceTests()
{
    // _fakeRepo = Substitute.For<IWmsCompanyRepository>();
    _supplierAppService = GetRequiredService<ISupplierAppService>();
}

protected override void AfterAddApplication(IServiceCollection services)
{
    _fakeRepo = Substitute.For<IWmsCompanyRepository>();
    services.AddSingleton(_fakeRepo);
}