Nestjs Provider with interface - dependency-injection

Question

I'm aware Nestjs like Angular, don't allow using interfaces as providers. How can I work around that ?
I wanted to maintain the interface as the provider, to test it more simpler, or to eventually change the databases for example a UserMongoDb. The database objects are in a separate lib, I can't change them to abstract classes.
interface UserDatabase {
create();
read();
}
class UserOracleDb implements UserDatabase {
create()
{
throw new Error("Method not implemented.");
}
read()
{
throw new Error("Method not implemented.");
}
}
#Injectable()
export class UserRepository {
constructor(private repository: UserDatabase)
}
// ... module.ts
{
providers: [
{
provide: Database,// Wants a class not an interface
useValue: new UserOracleDb('USER_TABLE')
}
]
}

Answer 1

After reading the docs, the answer is using the approach described here https://docs.nestjs.com/fundamentals/custom-providers#non-class-based-provider-tokens
In my case:
#Injectable()
export class UserRepository {
constructor(#Inject('USER_REPO') private repository: UserDatabase)
}
{
providers: [
{
provide: 'USER_REPO',
useValue: new UserOracleDb('USER_TABLE')
}
]
}

Answer 2

What if we declare an abstract class "implementing" the external interface and we declare all the methods as abstract. We avoid having literals linked to an interface.
Example:
export abstract class IUserDatabase implements UserDatabase{
abstract create();
abstract read();
}
class UserOracleDb implements IUserDatabase {
create()
{
throw new Error("Method not implemented.");
}
read()
{
throw new Error("Method not implemented.");
}
}
#Module({
providers: [{
provide: IUserDatabase,
useClass: UserOracleDb,
}]
})
#Injectable()
export class UserRepository {
constructor(private repository: IUserDatabase)
}