Test .NET6 minimal API with AutoMapper

I have a .NET6 project with minimal APIs. This is the code

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddDbContext<ClientContext>(opt => 
  opt.UseInMemoryDatabase("Clients"));
builder.Services
  .AddTransient<IClientRepository,
                ClientRepository>();
builder.Services
  .AddAutoMapper(Assembly.GetEntryAssembly());

var app = builder.Build();

// Get the Automapper, we can share this too
var mapper = app.Services.GetService<IMapper>();
if (mapper == null)
{
    throw new InvalidOperationException(
      "Mapper not found");
}

app.MapPost("/clients",
  async (ClientModel model,
         IClientRepository repo) =>
  {
      try
      {
          var newClient = mapper.Map<Client>(model);
          repo.Add(newClient);
          if (await repo.SaveAll())
          {
              return Results.Created(
                $"/clients/{newClient.Id}",
                mapper.Map<ClientModel>(newClient));
          }
      }
      catch (Exception ex)
      {
          logger.LogError(
            "Failed while creating client: {ex}",
            ex);
      }
      return Results.BadRequest(
        "Failed to create client");
  });

This code is working. I have a simple Profile for AutoMapper

public class ClientMappingProfile : Profile
{
    public ClientMappingProfile()
    {
        CreateMap<Client, ClientModel>()
          .ForMember(c => c.Address1, o => o.MapFrom(m => m.Address.Address1))
          .ForMember(c => c.Address2, o => o.MapFrom(m => m.Address.Address2))
          .ForMember(c => c.Address3, o => o.MapFrom(m => m.Address.Address3))
          .ForMember(c => c.CityTown, o => o.MapFrom(m => m.Address.CityTown))
          .ForMember(c => c.PostalCode, o => o.MapFrom(m => m.Address.PostalCode))
          .ForMember(c => c.Country, o => o.MapFrom(m => m.Address.Country))
          .ReverseMap();
    }
}

I wrote a NUnit test and a xUnit test. In both cases, when I call the API I receive the error

Program: Error: Failed while creating client: AutoMapper.AutoMapperMappingException: Missing type map configuration or unsupported mapping.

Mapping types: ClientModel -> Client MinimalApis.Models.ClientModel -> MinimalApis.Data.Entities.Client at lambda_method92(Closure , Object , Client , ResolutionContext )

How can I use the Profile in the main project? The full source code is on GitHub.

When you run your project normally, Assembly.GetEntryAssembly() will resolve to your project's assembly (the one that contains the Profile classes). When you launch your project via a unit test project, the entry point is actually that unit test.

That means that this code isn't actually finding the profiles because they're not in that assembly:

builder.Services
  .AddAutoMapper(Assembly.GetEntryAssembly());

Normally what I do in this situation is to use typeof(someAssemblyInMyProject).Assembly. In this example I use Program but any class should work so long as its in the same project as the Profile classes:

builder.Services
  .AddAutoMapper(typeof(Program).Assembly);

Now, no matter what the entry assembly is, you'll still find the right list of profiles.

Test .NET6 minimal API with AutoMapper

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