foreach (Assembly asm in AppDomain.CurrentDomain.GetAssemblies()) 
{
  //...
}

loadEntities(asm, modelBuilder, "نام فضا");

The entity type User is not part of the model for the current context.

namespace Test.Domain
{
    public abstract class BaseEntity
    {
        public int Id { set; get; }
    }
}

namespace Test.Domain.Entities
{
    public class User : BaseEntity
    {
        public int UserNumber { get; set; }
        public string Name { get; set; }
    }
}

namespace Test.Domain.Mappings
{
    public class UserMap : EntityTypeConfiguration<User>
    {
        public UserMap()
        {
            this.HasKey(x => x.UserNumber);
            this.Property(x => x.Name).HasMaxLength(450).IsRequired();
        }
    }
} 

   loadEntities(asm, modelBuilder, "Test.Domain");