Type extensions to help check for generic closure.

TypeExtensions.cs

public static class TypeExtensions
{
    public static bool Closes(this Type type, Type checkType)
    {
        if (!checkType.IsGenericTypeDefinition)
            throw new ArgumentException("Type being checked against is not an open generic type.");

        return
            type.IsGenericType
            && type.GetGenericTypeDefinition() == checkType;
    }

    public static IEnumerable<Type> InheritanceChain(this Type type)
    {
        yield return type;

        var currentType = type.BaseType;
        while (currentType != null)
        {
            yield return currentType;

            currentType = currentType.BaseType;
        }
    }

    public static bool Implements<T>(this Type type)
    {
        return type.Implements(typeof(T));
    }

    public static bool Implements(this Type type, Type check)
    {
        if (check.IsGenericTypeDefinition)
            return
                type.Closes(check)
                || type.InheritanceChain().Any(@class => @class.Closes(check))
                || type.GetInterfaces().Any(@interface => @interface.Closes(check));

        return check.IsAssignableFrom(type);
    }
}