抽象 ef core 2 dbContext

我正在尝试对我的数据库上下文层进行抽象(EntityFramework 2.0).

I'm trying to make an abstraction over my DB Context layer (EntityFramework 2.0).

Car.DataContext
 ------------------- 
 public abstract class BaseCarContext : DbContext
    {
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Car>(e =>
            {
                e.ToTable("Car");             
            });
            modelBuilder.Entity<Car>(e => { e.ToTable("Cars"); });
        }
    }

     public class CarContext : BaseCarContext
    {
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (optionsBuilder.IsConfigured)
                return;

            optionsBuilder.UseSqlServer(@"Server = xxxx; Database = xxxx; Trusted_Connection = True;");
        }

        public DbSet<Car> Cars { get; set; }        
    }

 Car.Logic
 ----------------
 public interface ICarService
 {
    GetCarResponse RetrieveCar(int id);
    void Save(int id);
    ...
 }

 public class CarService : ICarService
 {
    private readonly ICarService service;   
    // dbContext interface

    public CarService(ICarService service){
        this.service = service; 
        // injecting db context interface
    }

    public void Save(int id){
        ... saving using injected db context
        // injected db context.Insert(new Car{ Name = "Honda" });
    }
    ...
 }

我如何抽象这个 ef core 2 CarContext 以便使用 dbContext 保存

How can I abstract this ef core 2 CarContext in order to use dbContext save

我试图制作一个由CarContext实现的接口IDbContext但那样我就不能使用 dbContext.Cars.Insert 因为我没有实现 dbContext 汽车集合无法访问 ef 核心方法和属性.

I tried to make an interface IDbContext which is implemented by CarContext but that way I cannot use dbContext.Cars.Insert because I'm not implementing dbContext cars collection don't have access to ef core methods and properties.

我当然可以使用具体的实现，但我正在尝试进行抽象，以便我可以使用单元测试，...

I can use of course concrete implementation but I'm trying to make an abstraction so I can use unit tests, ...

你会怎么做?