This happens because of NSubstitute syntax specific. For example in: ((IQueryable<Blog>) mockSet).Provider.Returns(data.Provider); NSubstitute calls the Provider’s getter, then it specifies the return value. This getter call isn’t intercepted by the substitute and you get an exception. It happens because of explicit implementation of IQueryable.Provider property in DbQuery class. You can explicitly create substitutes for multiple … Read more
With Entity Framework Core (tested with Version 2.1) you can get the current context using // DbSet<MyModel> myDbSet var context = myDbSet.GetService<ICurrentDbContext>().Context; How to get a DbContext from a DbSet in EntityFramework Core 2.0
Find calls DetectChanges internally, SingleOrDefault (or generally any query) doesn’t. DetectChanges is an expensive operation, so that’s the reason why Find is slower (but it might become faster if the entity is already loaded into the context because Find would not run a query but just return the loaded entity). If you want to use … Read more