Introdução a padrões de projeto

Database.cs

public interface IDatabase<TEntity>
{
  Task SaveAsync(TEntity entity);
  Task<TEntity> Get(Guid id);
  Task<ICollection<TEntity>> GetAll();
  Task Delete(Guid id);
  Task<TEntity> Update(TEntity entity);
}

UserMongoDb.cs

public class UserMongoDb : IDatabase<User>
{
  Task SaveAsync(TEntity entity)
  {
    ...
  }
  Task<TEntity> Get(Guid id)
  {
    ...
  }
  Task<ICollection<TEntity>> GetAll()
  {
    ...
  }
  Task Delete(Guid id)
  {
    ...
  }
  Task<TEntity> Update(TEntity entity)
  {
    ...
  }
}

UserService.cs

public class UserService
{
  private readonly IDatabase<User> _database;

  public UserService(
    IDatabase<User> database
  )
  {
      _database = database;
  }
}