Working with AutoFixture

[peheje]

Has anyone gotten this package to work with AutoFixture to automatically create your test data?

Maybe with some type of generic AutoFixture specimen builder?

I believe AutoFixture would like the properties to be public set or for the object to have a public ctor.

[Ergamon]

I looked at the library today for evaluation.

The way AutoFixture works, it does not play nice with it. AutoFixture just sees a class with an empty constructor.

So indeed you need some kind of customization to tell AutoFixture to use the From method.

With a few minutes of coding I came up with this:

  public class ValueOfSpecimenBuilder : ISpecimenBuilder
  {
    private const string FactoryMethodName = "From";

    object ISpecimenBuilder.Create(object request, ISpecimenContext context)
    {
      var type = request as Type;

      var valueType = GetValueType(type);

      if(valueType is null)
      {
        return new NoSpecimen();
      }

      var value = context.Resolve(valueType);

      return Create(type, value);
    }

    private static object Create(Type type, object value)
    {
      var method = type.GetMethod(
        FactoryMethodName,
        BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy);

      var parameters = new object[]
      {
        value,
      };

      return method.Invoke(null, parameters);
    }

    private static Type GetValueType(Type type)
    {
      while (type != null)
      {
        if (type.IsGenericType)
        {
          var definition = type.GetGenericTypeDefinition();

          if (definition == typeof(ValueOf<,>))
          {
            var arguments = type.GetGenericArguments();
            return arguments[0];
          }
        }
        
        type = type.BaseType;
      }
      
      return null;
    }
  }

Probably some room for improvement, but it works.

  public class Gtin : ValueOf<string, Gtin>
  { 
  }

  var fixture = new Fixture();
  fixture.Customizations.Add(new ValueOfSpecimenBuilder());

  var gtin = fixture.Create<Gtin>();