I get an error like this when writing unit test

My product class is like this. I added virtual.

My map is like this.
SqlServerHelper like this.
I am using vs code 2022. I'm developing with Net 6.0 entity framework. I am getting this error while doing unit test. No errors in codes. Is it a problem with the version? Or Is there a logical error. what is the solution?


Problem solved. I wrote Db link instead of Northwind Context. :)