Improve the error message when parameter type is not registered

[akunzai]

Throws InvalidOperationException with following message when parameter type is not registered in ConstructorInjectionConvention:

The constructor of type '{modelType}' contains the parameter of type '{paramType}' is not registered, Ensure the type '{paramType}' are registered in additional services with CommandLineApplication.Conventions.UseConstructorInjection(IServiceProvider additionalServices)

Fix #174

[natemcmaster]

I agree it would be good to add better error messages, but I think this is a subtle breaking change for types which have multiple constructors. Let's try to preserve the current behavior.

I'm concerned about a scenario like this:

public class MyType
{
  public MyType(IService1 s1) { } // ctor A
  public MyType(IService1 s1, IService2 s2) { } // ctor B
}

If only IService1 were registered in the service provider, this convention would try first to use ctor B, and then fallback to ctor A. With your change, it would throw. I can see benefits to having a stricter behavior as the default, but I don't want to break existing users.

If you can think of a way to keep existing behavior and improve it, I'll reconsider. For example, adding a "strict mode" options flag, or throwing a better error after all constructors have been examined.

Thanks,
Nate

[akunzai]

Thanks @natemcmaster

I will study again to see how to deal with it better.

[akunzai]

Hi @natemcmaster,

Can we use ActivatorUtilities from Microsoft.Extensions.DependencyInjection.Abstractions to simplify this

[natemcmaster]

Thanks for updating the PR. This seems fine to me.

Can we use ActivatorUtilities from Microsoft.Extensions.DependencyInjection.Abstractions to simplify this

No. That would add a new dependency which I don't want this library to have.