There's more (and some less) in Entity Framework Core compared to Entity Framework 6, at least in version 1.0. While you can move to Entity Framework Core now, it might be too early for you.

How to use the InMemory provider in Entity Framework Core to test your methods without hitting the database or using fakes and mocks ...

The following is the DbContext class that can be generated automatically when you’re using Entity Framework Core. We’ll use this class several times in the code snippets that follow.