Abstracting ef core 2 dbContext - entity-framework

Question

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" });
}
...
}
How can I abstract this ef core 2 CarContext in order to use dbContext save
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.
I can use of course concrete implementation but I'm trying to make an abstraction so I can use unit tests, ...
How would you do this?

Answer 1

First, you don't need an abstraction to unit test. EF Core is 100% test-friendly. Second, the only truly acceptable abstractions, in my opinion for EF (or really any ORM) is either a microservice or the CQRS/event sourcing patterns. Those actually add value in that they either fully abstract the dependency and/or solve real line-of-business problems. However, those patterns also require a significant amount of effort to implement correctly, and as such, typically are reserved for large, complex applications.
Long and short, just use EF directly unless you have a truly good reason not to. Testing is not a good reason.