AndSpecification.cs

public class AndSpecification<TEntity> : Specification<TEntity>
{
    private readonly ISpecification<TEntity> leftSpecification;
    private readonly ISpecification<TEntity> rightSpecification;

	public AndSpecification(ISpecification<TEntity> leftSpecification, ISpecification<TEntity> rightSpecification)
	{
		this.leftSpecification = leftSpecification;
		this.rightSpecification = rightSpecification;
	}

	public override bool IsSatisfiedBy(TEntity entity)
	{
		return this.leftSpecification.IsSatisfiedBy(entity) && this.rightSpecification.IsSatisfiedBy(entity);
	}
}