AutoFixtureParameterSource.cs

public class AutoFixtureParameterSource : ParameterSource
{
    public IEnumerable<object[]> GetParameters(MethodInfo method)
    {
        // Produces a randomly-populated object for each
        // parameter declared on the test method, using
        // a Fixture that has our customizations.

        var fixture = new Fixture();

        CustomizeAutoFixture(fixture);

        var specimenContext = new SpecimenContext(fixture);

        var allEntitiesAttribute =
           method.GetCustomAttributes<AllEntities>(true).SingleOrDefault();

        if (allEntitiesAttribute != null)
        {
            return typeof(Entity).Assembly.GetTypes()
                .Where(t => t.IsSubclassOf(typeof(Entity)))
                .Where(t => !t.IsAbstract)
                .Except(allEntitiesAttribute.Except)
                .Select(entityType => new[] { specimenContext.Resolve(entityType) })
                .ToArray();
        }

        var parameterTypes = method.GetParameters().Select(x => x.ParameterType);

        var arguments = parameterTypes.Select(specimenContext.Resolve).ToArray();

        return new[] { arguments };
    }

    private static void CustomizeAutoFixture(Fixture fixture)
    {
        var propertyBuilders = typeof(PropertyBuilder)
            .Assembly
            .GetTypes()
            .Where(t => !t.IsAbstract && typeof(ISpecimenBuilder).IsAssignableFrom(t))
            .Select(Activator.CreateInstance)
            .Cast<ISpecimenBuilder>();

        foreach (var propertyBuilder in propertyBuilders)
            fixture.Customizations.Add(propertyBuilder);
    }
}

[AttributeUsage(AttributeTargets.Method)]
class AllEntities : Attribute
{
    public AllEntities()
    {
        Except = new Type[] { };
    }

    public Type[] Except { get; set; }
}